0:00:02 > 0:00:04Rome, for 1,000 years
0:00:04 > 0:00:06the beating heart of the ancient world.
0:00:08 > 0:00:12Capital city of the most powerful empire on the planet.
0:00:13 > 0:00:17But this iconic cityscape tells only half the story.
0:00:17 > 0:00:21Every modern city is served by its underground spaces.
0:00:22 > 0:00:262,000 years ago, the Romans got there before us.
0:00:28 > 0:00:30Deep beneath Rome's glorious domes
0:00:30 > 0:00:34and columns lies a secret underground powerhouse that
0:00:34 > 0:00:38made life possible for a million citizens up above.
0:00:42 > 0:00:48I love Rome. Of all the places in the world this is my favourite.
0:00:50 > 0:00:54Every time I visit I find myself just newly bewitched by
0:00:54 > 0:00:56this fantastic ancient city.
0:00:56 > 0:01:00But this time I'll go beyond the surface world that
0:01:00 > 0:01:03the tourists see and the archaeologists scrape at.
0:01:04 > 0:01:09I'll be digging deeper to explore a whole new invisible world deep
0:01:09 > 0:01:14underground that reveals how the first metropolis was built and run.
0:01:15 > 0:01:18Wow. It leads down eight storeys.
0:01:21 > 0:01:24Xander, are you all right down there?
0:01:24 > 0:01:25Fine.
0:01:25 > 0:01:29'I'll be working with a team of experts who'll use the latest
0:01:29 > 0:01:32'technology to reveal this secret underworld.'
0:01:32 > 0:01:34Look at this.
0:01:34 > 0:01:36That's incredible. Look at the detail.
0:01:36 > 0:01:40'We'll explore the underground engine rooms that built
0:01:40 > 0:01:43'and powered the extraordinary world above...'
0:01:43 > 0:01:47Everything that made Rome tick is coming along these passageways.
0:01:47 > 0:01:51'..the hidden wonders below the Coliseum that made it the greatest
0:01:51 > 0:01:53'and the goriest show on earth.
0:01:55 > 0:02:00'And in long-lost labyrinths we'll uncover underground cults.
0:02:00 > 0:02:04'This invisible treasure trove will reveal the secrets
0:02:04 > 0:02:08'of the world's most remarkable ancient city both below...'
0:02:08 > 0:02:11I've never been in a sewer before. I hear it's great(!)
0:02:11 > 0:02:12'..and above ground.'
0:02:14 > 0:02:16Welcome to invisible Rome.
0:02:33 > 0:02:34Now, this is enormous fun.
0:02:34 > 0:02:37I used to drive one of these for about seven years in London.
0:02:37 > 0:02:39My wife made me get rid of it when we had children. Why?
0:02:39 > 0:02:41Did she think it was dangerous or something(?)
0:02:41 > 0:02:43Anyway, this is the best way to get around Rome.
0:02:43 > 0:02:45If you've been around Hyde Park Corner
0:02:45 > 0:02:48getting around Piazza del Popolo is going to hold no fear for me.
0:02:48 > 0:02:51Here we go. Let the dog see the rabbit.
0:03:00 > 0:03:04I've always loved this city,
0:03:04 > 0:03:07ever since I was a child and my grandfather used to read to us
0:03:07 > 0:03:12from the legends of ancient Rome. I even had my honeymoon here.
0:03:12 > 0:03:17Who could resist the majesty of the Forum, the Coliseum
0:03:17 > 0:03:19and St Peter's Basilica?
0:03:23 > 0:03:27But now I'm going to dive into the underground spaces
0:03:27 > 0:03:31we don't see on the surface to discover exactly how
0:03:31 > 0:03:34the underworld powered the first metropolis.
0:03:45 > 0:03:48My walking Wikipedia for this exploration of invisible Rome
0:03:48 > 0:03:50is Dr Michael Scott.
0:03:52 > 0:03:56Michael's been coming here for 15 years to study the city's
0:03:56 > 0:03:57amazing monuments.
0:04:02 > 0:04:04And where better to start our journey into Rome's
0:04:04 > 0:04:08underworld than in its largest and most famous building,
0:04:08 > 0:04:10the Coliseum?
0:04:14 > 0:04:18It opened in 80 AD, just as Rome reached the height of its powers.
0:04:20 > 0:04:21Look at that.
0:04:22 > 0:04:26'For 500 years it hosted a gladiatorial carnival of combat
0:04:26 > 0:04:28'and carnage.'
0:04:28 > 0:04:31- So, Xander, welcome to the Coliseum. - Wow!
0:04:31 > 0:04:34This is where you hear the roar, isn't it?
0:04:34 > 0:04:37Something like 60,000 people on the seats all around us...
0:04:37 > 0:04:4060,000 in a city of a million is a significant percentage, isn't it?
0:04:40 > 0:04:43..all baying and shouting loudly for what was going to take place
0:04:43 > 0:04:45right here on the arena floor.
0:04:45 > 0:04:48And this place opens with 100 days of games.
0:04:48 > 0:04:54And can you imagine what it must have felt like to be standing on the arena itself?
0:04:54 > 0:04:58And the noise, the wall of noise of the people all around.
0:05:06 > 0:05:08'Standing on the arena floor gives me
0:05:08 > 0:05:11'a spooky sense of the spectacle that unfolded here.
0:05:14 > 0:05:17'But to understand how the Coliseum really worked,
0:05:17 > 0:05:20'we have to go down into the bowels of the beast.'
0:05:26 > 0:05:28This is called the Hypogeum.
0:05:28 > 0:05:31It just means underground space.
0:05:31 > 0:05:33There's a tunnel that goes all the way out there
0:05:33 > 0:05:37- and that leads to the gladiator school.- Right.
0:05:37 > 0:05:41So we're walking in the footsteps of the gladiators
0:05:41 > 0:05:44who would have been coming into the Coliseum.
0:05:44 > 0:05:47A tiny proportion of who might get to walk back that way, as well.
0:05:47 > 0:05:51Yeah, there was also an exit to the morgue.
0:05:53 > 0:05:57'These tunnels aren't the only hidden secrets of the Coliseum.
0:05:57 > 0:06:01'Beneath the stage was a labyrinth of holding pens and lift shafts.'
0:06:03 > 0:06:05Well, if I show you.
0:06:05 > 0:06:08This is the arena floor, this is the bit above us, right.
0:06:08 > 0:06:13There would have been these holes that opened up, about 40 of them,
0:06:13 > 0:06:17and these correspond to these tunnels that we're looking at directly.
0:06:17 > 0:06:22Underneath each of these, we can start to see the mechanisms.
0:06:23 > 0:06:28'These crumbling ruins were once at the cutting edge of technology.
0:06:28 > 0:06:32'In the central corridor, sloping rails guided monumental
0:06:32 > 0:06:34'scenery up onto the stage above.
0:06:36 > 0:06:39'On either side, numerous lift shafts disgorged animals
0:06:39 > 0:06:42'and humans to their deaths in the arena.'
0:06:47 > 0:06:50- Can you see that hole in the ground, the central hole?- Yeah.
0:06:50 > 0:06:54That's probably the hole where a capstan pole went up two floors
0:06:54 > 0:06:58and had big arms so that two teams of men could turn it
0:06:58 > 0:07:02and that would be used as a winch to lift up cages.
0:07:02 > 0:07:04How incredible!
0:07:04 > 0:07:06These lifts would have been big enough to take anything up to a lion.
0:07:06 > 0:07:09These animals would just magically appear.
0:07:09 > 0:07:15This would have been a sea of machinery, toil, effort, noise.
0:07:15 > 0:07:18The animals starved so that they were extra hungry
0:07:18 > 0:07:20when they got out there onto the arena floor.
0:07:20 > 0:07:23You know, I've been backstage in a lot of theatres
0:07:23 > 0:07:25and the atmosphere backstage, particularly with a big show,
0:07:25 > 0:07:28nothing as complex as this but, you know, you've got people
0:07:28 > 0:07:31running around with clipboards getting terribly panicked.
0:07:31 > 0:07:34I guess if you times that by 100...
0:07:34 > 0:07:37If these guys down here, the guys operating the machinery,
0:07:37 > 0:07:40the guys calling the timing, got it wrong, they could find
0:07:40 > 0:07:44themselves not running the spectacle but being the spectacle!
0:07:44 > 0:07:47- They were the next ones on(?) - The next ones to be fed.- Blimey!
0:07:47 > 0:07:51- It's not just about not getting a bouquet of flowers at the curtain call.- No.
0:07:51 > 0:07:55It's just so macabre, isn't it? The spectacle ultimately is death.
0:07:59 > 0:08:03'Over the lifetime of the Coliseum, it's believed that up to
0:08:03 > 0:08:07'500,000 people and one million animals were slaughtered here.'
0:08:07 > 0:08:11To have something like this right at the heart of Roman life,
0:08:11 > 0:08:16it smacks of a certain hedonism spiralling out of control, slightly.
0:08:16 > 0:08:19There was nothing out of control about this environment.
0:08:19 > 0:08:23The Emperor paid to put on these games to demonstrate his power,
0:08:23 > 0:08:25- his control.- Mmm.
0:08:25 > 0:08:28He did it to ensure that the people,
0:08:28 > 0:08:31the mob of Rome in some ways, were on his side.
0:08:31 > 0:08:33How do you keep the people happy?
0:08:33 > 0:08:36- You feed them, you keep them entertained.- Bread and circuses.
0:08:36 > 0:08:38Stopped them giving him trouble.
0:08:38 > 0:08:40A none too subtle way of saying,
0:08:40 > 0:08:43"You stick on side or else it'll be you hanging out of the lion's mouth!"
0:08:48 > 0:08:50I think if I'd just seen this above ground,
0:08:50 > 0:08:53I'd have seen the spectacle, the scale.
0:08:53 > 0:08:57I'd have thought of this as a piece of bravura architecture
0:08:57 > 0:08:58but then you go below stairs...
0:09:00 > 0:09:04You get that horrific macabre sense of this being a machine
0:09:04 > 0:09:07that spewed people out to their certain deaths.
0:09:09 > 0:09:12'After the underground world of the Coliseum,
0:09:12 > 0:09:15'I can't wait to see what more this worm's eye view
0:09:15 > 0:09:17'can tell me about the rest of invisible Rome.'
0:09:24 > 0:09:29'But first, time for a more modern traditional Roman pick-me-up.'
0:09:32 > 0:09:36You can come here and see so much of Ancient Rome
0:09:36 > 0:09:40up on top of ground. The Coliseum is a perfect example.
0:09:40 > 0:09:43- You knew the Coliseum.- I did. I had seen it, visible Rome.
0:09:43 > 0:09:46Visible, Ancient Rome is all around us
0:09:46 > 0:09:50and the thing that really excites me about this is we have got to go back underground
0:09:50 > 0:09:55if we want to really understand how Rome became the amazing city it did.
0:09:55 > 0:09:58We are going to be working with a team of 3D laser scanners,
0:09:58 > 0:10:00- cutting edge technology. - This is very exciting, indeed.
0:10:00 > 0:10:02That is going to, for the very first time in Rome,
0:10:02 > 0:10:06be mapping some of the underground spaces we are going into,
0:10:06 > 0:10:10in a level of detail, texture, colour that has never been done before.
0:10:10 > 0:10:13OK, so I can get my head around that, of course, underground,
0:10:13 > 0:10:17one accepts that a great deal going on under there.
0:10:17 > 0:10:19How do we get underground?
0:10:19 > 0:10:22We're going to be walking through the streets of everyday Rome and
0:10:22 > 0:10:26just there's going to be something completely that you'd pass by without
0:10:26 > 0:10:30even noticing, access points for us to the world of invisible Rome.
0:10:30 > 0:10:31This is like the Time Bandits.
0:10:31 > 0:10:34Sometimes it might be slightly more complicated.
0:10:34 > 0:10:37- You're not claustrophobic, are you? - No.
0:10:37 > 0:10:39How's your abseiling?
0:10:39 > 0:10:40Abseiling(?)
0:10:40 > 0:10:42You brought the Flavia.
0:10:42 > 0:10:43I don't drive a Vespa...
0:10:43 > 0:10:45'So, now I'm buzzing with espresso,
0:10:45 > 0:10:49'I'm ready for invisible Rome to reveal itself.
0:10:49 > 0:10:51'I'm hitching a lift with the Prof.'
0:10:54 > 0:10:57How do we know what's there? I mean...
0:10:57 > 0:11:02Sometimes we need some kind of like natural disaster
0:11:02 > 0:11:07to uncover a bit of underground Rome that we didn't even know existed.
0:11:07 > 0:11:12'It seems the city is so peppered with undiscovered subterranean spaces,
0:11:12 > 0:11:16'that people and buildings just keep falling into sinkholes.
0:11:17 > 0:11:20'We're on our way to the Aventine Hill,
0:11:20 > 0:11:22'one of the seven hills Rome was built on.
0:11:25 > 0:11:29'According to legend, it was founded by brothers Romulus and Remus,
0:11:29 > 0:11:33'who were suckled by a she-wolf in a cave close by.'
0:11:33 > 0:11:38Now we're going to see a little sink hole.
0:11:38 > 0:11:41'Marco gets the call when random bits of the city
0:11:41 > 0:11:43'disappear into the ground.'
0:11:45 > 0:11:46Look at this!
0:11:46 > 0:11:50- What actually has happened? - This collapsed in the night.
0:11:51 > 0:11:55When one of these people go in the morning to work,
0:11:55 > 0:11:59and found this situation.
0:11:59 > 0:12:02- It's gone. - I'm assured that it is man-made.
0:12:02 > 0:12:03- Man-made?- Yes.
0:12:03 > 0:12:08So Marco, how many sinkholes like this appeared last year, let's say?
0:12:08 > 0:12:15Last year, we have 80 sink holes.
0:12:15 > 0:12:18- 80?- 80.- Eight zero?
0:12:18 > 0:12:20- We have many more.- Already?
0:12:20 > 0:12:23'Michael isn't surprised that Ancient Rome is devouring
0:12:23 > 0:12:25'so much of the modern city.'
0:12:26 > 0:12:29There was a city of one million people in Ancient Rome.
0:12:29 > 0:12:34The population density was ten times what London is today.
0:12:34 > 0:12:36There is so much still to find
0:12:36 > 0:12:41and it's moments like this that open up new windows.
0:12:41 > 0:12:44So when something happens like this, it's a sort of God-given opportunity
0:12:44 > 0:12:47for archaeologists to roll up their sleeves and have a sneak peek.
0:12:47 > 0:12:49It's very exciting.
0:12:51 > 0:12:54'Marco has got a lead on what's causing the trouble.
0:12:54 > 0:12:56'It's just around the corner.
0:12:56 > 0:12:59'This is where our 3D scanners will start revealing
0:12:59 > 0:13:01'the secrets of Rome's underground spaces.
0:13:03 > 0:13:05'Not so long ago,
0:13:05 > 0:13:08'another collapse revealed an ancient underground quarry.
0:13:08 > 0:13:11'Today there's precious little sign of it
0:13:11 > 0:13:13'in these quiet, suburban streets.'
0:13:16 > 0:13:18I'm not quite sure where this quarry's going to be.
0:13:18 > 0:13:21- The quarry is there. - It's in there? Is it a quarry?
0:13:21 > 0:13:23No, it's under your feet.
0:13:25 > 0:13:26No, that(!)
0:13:30 > 0:13:33That's what's underneath all these manholes.
0:13:33 > 0:13:35I had no idea, I thought it was utilities.
0:13:35 > 0:13:38I think it's 20 metres.
0:13:38 > 0:13:42That's about an eight-storey building underground.
0:13:42 > 0:13:45I'm going to step back and think about that for a moment.
0:13:45 > 0:13:46That's extraordinary.
0:13:46 > 0:13:50Just in this very unassuming little side street,
0:13:50 > 0:13:53there's this manhole cover, unlocked,
0:13:53 > 0:13:56that leads down eight storeys.
0:13:58 > 0:14:02'It's time for the scanning team to swing into action.
0:14:02 > 0:14:05'They're making the first of our 3D scans to help us
0:14:05 > 0:14:07'reveal this invisible world.'
0:14:08 > 0:14:11As we stand as the blue and red men.
0:14:11 > 0:14:14Hot and cold, Michael. Hot and cold.
0:14:14 > 0:14:16How do you feel?
0:14:16 > 0:14:18Hot and cold, actually.
0:14:18 > 0:14:20It was very good of you to agree to go down first.
0:14:22 > 0:14:24I think once I'm over the first...
0:14:24 > 0:14:27Argh! I think it might be quite fun.
0:14:27 > 0:14:29Good. That's spot on.
0:14:31 > 0:14:33There we are.
0:14:42 > 0:14:44Xander, are you all right down there?
0:14:44 > 0:14:46It's fine!
0:14:49 > 0:14:52It's absolutely fine.
0:14:55 > 0:14:57OK, down I come.
0:15:03 > 0:15:05Oh, blimey!
0:15:05 > 0:15:07HE CHUCKLES
0:15:07 > 0:15:08This is great.
0:15:08 > 0:15:12You knew all about this? Oh, God, it's amazing.
0:15:12 > 0:15:15I wasn't expecting anything as big as this.
0:15:15 > 0:15:18Look at that. Amazing!
0:15:18 > 0:15:20Look, it just goes on.
0:15:20 > 0:15:21And on.
0:15:22 > 0:15:26'This place would once have teemed with hundreds of slaves
0:15:26 > 0:15:28'working under the lash.
0:15:28 > 0:15:31'Today, we're setting our scanners to work.'
0:15:38 > 0:15:41'Matt Shaw explains how the technology works.'
0:15:42 > 0:15:44We're laser scanning the caves
0:15:44 > 0:15:46so what that means is taking millions and millions
0:15:46 > 0:15:51of measurements of the surface down to a level of detail of every millimetre.
0:15:51 > 0:15:54It allows us to assemble a model of the complete 3D
0:15:54 > 0:15:56geometry of the caverns.
0:15:56 > 0:16:01These places are incredibly complex and very strange shapes.
0:16:01 > 0:16:03The laser is amazing at understanding those strange forms
0:16:03 > 0:16:06but we're also able to scan above ground
0:16:06 > 0:16:09and relate those above ground spaces to the places down here.
0:16:09 > 0:16:12'As the lasers map this jumble of rocks,
0:16:12 > 0:16:15'Michael shows me why this underground space
0:16:15 > 0:16:18'was so important to the Roman world above ground.'
0:16:19 > 0:16:23What particularly were they quarrying here?
0:16:23 > 0:16:27Everything that surrounds us is a particular volcanic rock.
0:16:27 > 0:16:30It's tufo, and that's what most of Rome is built on.
0:16:30 > 0:16:33That's what they wanted from down here.
0:16:33 > 0:16:36'Tufo hardens when exposed to the air,
0:16:36 > 0:16:38'an ideal building stone.
0:16:39 > 0:16:42'But also, in layers between the tufo,
0:16:42 > 0:16:44'is a less compacted volcanic ash.
0:16:45 > 0:16:48'If tufo built Rome,
0:16:48 > 0:16:50'then this stuff helped it conquer the world.'
0:16:52 > 0:16:54It's called in Italian, pozzolana.
0:16:54 > 0:16:58A secret Roman ingredient in making Roman concrete.
0:16:58 > 0:17:00The Romans were making concrete(?)
0:17:00 > 0:17:03The Romans were making concrete 2,000 years ago.
0:17:03 > 0:17:07'Concrete, as we know it, wasn't rediscovered until the 19th century.'
0:17:07 > 0:17:10No wonder that's why they send people down 20 metres to mine the stuff.
0:17:10 > 0:17:13With concrete they can build structures that no-one had
0:17:13 > 0:17:15ever dreamed possible.
0:17:16 > 0:17:19'Here the miners' pick marks are still just visible.
0:17:21 > 0:17:24'But to make sense of this space, we really need the scans.
0:17:26 > 0:17:29'They can record everything from the most minute detail to
0:17:29 > 0:17:32'the labyrinth of interconnected chambers where the slaves
0:17:32 > 0:17:34'would have toiled.
0:17:34 > 0:17:39'Above a giant spoil heap, there's another intriguing feature.'
0:17:39 > 0:17:42What we come to, we think,
0:17:42 > 0:17:46is an Ancient Roman exit.
0:17:46 > 0:17:48Look, and there it is.
0:17:48 > 0:17:49The timbers covering it.
0:17:49 > 0:17:52The timbers of probably some guy's basement.
0:17:52 > 0:17:56He doesn't realise that underneath his floorboards is the entrance to a Roman quarry.
0:17:56 > 0:17:59When they walk across and hear that weird creak, they never realise...
0:17:59 > 0:18:02"Here are a couple of presenters below. I wonder what's going on?
0:18:02 > 0:18:05"Oi! Turn it down!"
0:18:05 > 0:18:07Can you see these little handholds, footholds,
0:18:07 > 0:18:11- as some poor guy had to clamber his way out...- Yeah.
0:18:11 > 0:18:15..taking the stuff to the surface to turn it into...
0:18:15 > 0:18:17- Turn it into an empire.- Yeah.
0:18:23 > 0:18:25'Scrambling around an ancient quarry has given me
0:18:25 > 0:18:28'an insight into Rome's geological good fortune.
0:18:30 > 0:18:34'Now I'm keen to seek how the 3D scan shines a light
0:18:34 > 0:18:36'on this part of invisible Rome.'
0:18:36 > 0:18:38Matt, how are you doing?
0:18:38 > 0:18:41'Matt has been processing the results.'
0:18:41 > 0:18:43I'm so excited about this.
0:18:43 > 0:18:46You should recognise, I think, this little place that we're looking at.
0:18:46 > 0:18:49That's right, the house where the sinkhole had appeared.
0:18:49 > 0:18:50If we pull out there.
0:18:50 > 0:18:54We are looking at a large section of Aventine Hill here.
0:18:54 > 0:18:57'The team have stitched together individual scans to make
0:18:57 > 0:19:00'a 3D model of the hill.'
0:19:01 > 0:19:05That is just a terrifyingly sophisticated tool, isn't it?
0:19:05 > 0:19:06It is amazing.
0:19:06 > 0:19:09From a millimetre detail, right the way out to a view
0:19:09 > 0:19:12that's spanning half a kilometre of the city.
0:19:17 > 0:19:18You may recognise...
0:19:19 > 0:19:21Look at this.
0:19:21 > 0:19:22This little manhole cover.
0:19:22 > 0:19:24There we are. Yes, I do recognise...
0:19:24 > 0:19:27And something lurking below the screen, as well.
0:19:27 > 0:19:30I'm never going to stand on a manhole cover again.
0:19:30 > 0:19:32There it is!
0:19:36 > 0:19:39'This is Rome like I've never seen it before.
0:19:39 > 0:19:42'The city and its invisible underground spaces
0:19:42 > 0:19:45'connected to each other.
0:19:45 > 0:19:49'And now we're in the quarry, it is like a light has been turned on.'
0:19:49 > 0:19:52Blimey, Matt, look at the detail.
0:19:52 > 0:19:55How extraordinary, and this maps it completely
0:19:55 > 0:19:58accurately in terms of its relationship with the above ground?
0:19:58 > 0:19:59Exactly, yeah.
0:19:59 > 0:20:01I see exactly where you are now,
0:20:01 > 0:20:04that's where we went up to what was possibly the original access.
0:20:04 > 0:20:07It looked very much as though that might be someone's cellar,
0:20:07 > 0:20:09or something like that. You were tempted to knock.
0:20:09 > 0:20:12'We learnt later we were under a convent.
0:20:12 > 0:20:15'Now that would have given the Mother Superior a shock(!)'
0:20:15 > 0:20:18If I were a householder on Aventine Hill,
0:20:18 > 0:20:21one of these rather smart residences, I think
0:20:21 > 0:20:26this is a map that would probably keep me awake at night.
0:20:26 > 0:20:29Yeah, I think it's amazing, this kind of network of strange,
0:20:29 > 0:20:31- organic spaces underground. - Yeah, yeah.
0:20:31 > 0:20:34And then this very rigid street pattern.
0:20:34 > 0:20:39- The grid of streets above and this ginger route beneath ground.- Yeah.
0:20:39 > 0:20:41- Exactly.- It's extraordinary.
0:20:41 > 0:20:43So we're building up this kind of strange underground map
0:20:43 > 0:20:45and above-ground map simultaneously
0:20:45 > 0:20:47and they're starting to fill in all these patches together.
0:20:47 > 0:20:50That's never been done before. God, that's incredible!
0:20:51 > 0:20:55'So an amazing amount of information for archaeologists,
0:20:55 > 0:20:56'surveyors and...
0:20:56 > 0:20:58'..burglars(?)'
0:20:58 > 0:21:01Wow, I feel like I should be sitting back in my chair
0:21:01 > 0:21:04and stroking a cat and saying, "Moo, ha-ha, ha..."
0:21:04 > 0:21:07We've taken this quiet, residential area of Rome
0:21:07 > 0:21:09and we've turned it into our plaything.
0:21:09 > 0:21:11This is incredible, isn't it?
0:21:11 > 0:21:13And to have that above and below ground perspective
0:21:13 > 0:21:15and see how they interrelate.
0:21:15 > 0:21:17I mean, what a resource.
0:21:17 > 0:21:19I can think of so many uses for this.
0:21:19 > 0:21:20But, most importantly,
0:21:20 > 0:21:24it allows us to build up our map of invisible underground Rome.
0:21:27 > 0:21:33'This quarry alone produced at least 6,000 tonnes of tufo and pozzolana.
0:21:33 > 0:21:36'It was part of a network spreading underneath the city,
0:21:36 > 0:21:39'like this one we scanned next to the Coliseum.
0:21:44 > 0:21:48'So far we've discovered 94 of the underground quarries
0:21:48 > 0:21:50'that helped build Rome.
0:21:50 > 0:21:52'It's like the metropolis is constructed
0:21:52 > 0:21:55'on an enormous Swiss cheese.
0:22:00 > 0:22:03'I'm rather fascinated by this pozzolana.
0:22:03 > 0:22:05'I really want to find out what the Romans did with it
0:22:05 > 0:22:09'and where better to discover how humble pozzolana
0:22:09 > 0:22:11'helped build the Roman Empire,
0:22:11 > 0:22:15'than in the most enduring of all their monumental buildings?
0:22:17 > 0:22:21'For 2,000 years, the Pantheon has been a pagan temple,
0:22:21 > 0:22:24'a church and then a tomb for Italian kings.
0:22:26 > 0:22:30'It was completed in 126 AD when Rome ruled an empire that
0:22:30 > 0:22:33'stretched from Portugal to Persia,
0:22:33 > 0:22:36'from Scotland to the Sahara.
0:22:44 > 0:22:47'I'm exploring this remarkable building with architectural
0:22:47 > 0:22:50'historian Professor Ettore Mazzola.'
0:22:57 > 0:23:00This is quite magnificent.
0:23:00 > 0:23:03- Even without knowing its antiquity. - Yeah.
0:23:03 > 0:23:05- It is staggering.- It's fantastic.
0:23:05 > 0:23:08It's one of the greatest ancient Roman buildings,
0:23:08 > 0:23:11extremely well preserved.
0:23:11 > 0:23:13- Such an acoustic.- Fantastic.
0:23:14 > 0:23:17'The interior is a vast cylinder
0:23:17 > 0:23:21'but its crowning glory is the dome.
0:23:21 > 0:23:24This is still today the largest,
0:23:24 > 0:23:27unreinforced concrete dome
0:23:27 > 0:23:30ever built on this planet.
0:23:30 > 0:23:33It's something that it is possible only because of the material
0:23:33 > 0:23:36and the technique used to build it.
0:23:36 > 0:23:40'Without steel to reinforce the concrete from within,
0:23:40 > 0:23:44'surely this dome should collapse under its own weight(?)'
0:23:44 > 0:23:47The whole structure is standing on eight pillars
0:23:47 > 0:23:51and you have load-spreading arches that are concentrating all
0:23:51 > 0:23:54the forces vertically into the pillars.
0:23:57 > 0:24:00'What ensures these walls can bear the load without buttresses,
0:24:00 > 0:24:03'is the construction of the dome itself.
0:24:03 > 0:24:07'Each of its layers is made with a slightly different mix of concrete.'
0:24:09 > 0:24:12The trick of these is to use different materials with
0:24:12 > 0:24:14a different weight.
0:24:14 > 0:24:19In this model you can see how step-by-step the dome is growing,
0:24:19 > 0:24:24so the first part is made up of Roman concrete
0:24:24 > 0:24:28that has inside fragments of travertine stone
0:24:28 > 0:24:31and tofu stone, which are very compact.
0:24:31 > 0:24:34And step-by-step these materials are getting lighter
0:24:34 > 0:24:37and then, at the very end, there is only the pumice stone
0:24:37 > 0:24:39which is closing the structure.
0:24:39 > 0:24:42- It gets lighter and lighter. - Lighter and lighter.
0:24:42 > 0:24:44Then, at the very top, there is this big hole,
0:24:44 > 0:24:48which is nine metres in diameter,
0:24:48 > 0:24:53which is necessary structurally also because all the forces, step-by-step,
0:24:53 > 0:24:56are going down vertically into the pillars.
0:24:58 > 0:25:01It's such a clever use of the raw materials
0:25:01 > 0:25:03found beneath Rome's streets.
0:25:03 > 0:25:05And it's still standing.
0:25:09 > 0:25:13Our modern concretes can succumb after as little as 20 years.
0:25:15 > 0:25:19What is it that makes Roman concrete last two millennia and beyond?
0:25:26 > 0:25:29Michael has come to a modern quarry outside Rome
0:25:29 > 0:25:32to find out how Roman concrete changed the world.
0:25:34 > 0:25:38The same types of rocks dug out of the quarry we explored earlier
0:25:38 > 0:25:40are still being quarried here today.
0:25:43 > 0:25:45With experimental archaeologist Lara Comis,
0:25:45 > 0:25:47he's going to make concrete
0:25:47 > 0:25:50using a Roman recipe that's 2,000 years old.
0:25:53 > 0:25:56- We have the recipe that says that we need quicklime.- OK.
0:25:56 > 0:25:58- This is quicklime.- This is the one.
0:25:58 > 0:26:03And it's basically made of rocks which have been fired in a kiln.
0:26:03 > 0:26:07- And here we have pozzolana. - So, this is pozzolana.
0:26:07 > 0:26:11- This is the secret ingredient in Roman concrete.- Yes, absolutely.
0:26:11 > 0:26:13The aggregate, the material that bulks up
0:26:13 > 0:26:14and strengthens the concrete,
0:26:14 > 0:26:16is the good old Roman tufo
0:26:16 > 0:26:18we also found in the ancient underground quarry.
0:26:18 > 0:26:20Do that there.
0:26:20 > 0:26:23When the quicklime is mixed with water and pozzolana,
0:26:23 > 0:26:26a reaction occurs that binds them together.
0:26:29 > 0:26:33Pozzolana contains naturally occurring oxides
0:26:33 > 0:26:36that create an even more durable mesh than modern concrete.
0:26:39 > 0:26:42Ah, now we're starting to create something.
0:26:42 > 0:26:43One...
0:26:46 > 0:26:47Two?
0:26:49 > 0:26:52So, how long will this take to dry?
0:26:52 > 0:26:54Well, actually, we think that the minimum
0:26:54 > 0:26:56- should be for 24 hours.- OK.
0:26:58 > 0:27:002,000 years ago, the Romans discovered
0:27:00 > 0:27:05that their special concrete mix doesn't even need air to dry it.
0:27:05 > 0:27:10Pozzolana has got his wonderful property to dry under the water.
0:27:10 > 0:27:14- The miraculous pozzolana. It really can do everything, can't it?- It can.
0:27:14 > 0:27:15And if you want,
0:27:15 > 0:27:19I can show you an experiment that has been set in the water.
0:27:19 > 0:27:22- OK.- So, we can actually try and see what happened.- OK.
0:27:22 > 0:27:25It's been setting for just 36 hours.
0:27:25 > 0:27:27..That one. Stuff on there.
0:27:27 > 0:27:31But will the concrete pass the test?
0:27:31 > 0:27:33- BOTH:- Wow!
0:27:33 > 0:27:36OK, I don't know about this colour. I'm not convinced. Hang on.
0:27:36 > 0:27:39- Well, try.- Actually, wow! - You see?- My God, you can just...!
0:27:39 > 0:27:41Bellissimo.
0:27:41 > 0:27:44- Yeah. - I'm beginning to be a believer.
0:27:44 > 0:27:50- I think that you can actually try, you know...- Three, two, one...
0:27:51 > 0:27:56- Wow!- Wow! That's ama... Look at that!- It's incredible.
0:27:56 > 0:28:03Standing on Roman concrete that has set underwater in 36 hours.
0:28:03 > 0:28:08The Romans, what technology! 2,000 years on, this is sensational.
0:28:08 > 0:28:12Using concrete that could set underwater,
0:28:12 > 0:28:15the Romans built the harbours and bridges
0:28:15 > 0:28:19that enabled them to dominate one quarter of the world's population.
0:28:19 > 0:28:20Wow!
0:28:20 > 0:28:23The Romans were the first to take this technology
0:28:23 > 0:28:25and to use it on a scale that others had only dreamt of,
0:28:25 > 0:28:28whether it be above ground or underwater.
0:28:28 > 0:28:30And in doing so, in thinking big,
0:28:30 > 0:28:34they were able to create an empire that controlled the Mediterranean
0:28:34 > 0:28:36and to create monuments and structures
0:28:36 > 0:28:38that have lasted for 2,000 years
0:28:38 > 0:28:41and will probably last for a lot longer to come.
0:28:44 > 0:28:45The Romans were so passionate
0:28:45 > 0:28:48about their buildings, harbours and bridges
0:28:48 > 0:28:52that the emperor took the title of Pontifex Maximus,
0:28:52 > 0:28:55the greatest bridge-builder -
0:28:55 > 0:28:58a title still used by popes to this day.
0:29:07 > 0:29:10The resources found beneath Rome's feet
0:29:10 > 0:29:13helped it build the world's first metropolis.
0:29:16 > 0:29:19But the city also needed the underworld
0:29:19 > 0:29:21to help it survive and prosper.
0:29:23 > 0:29:25Ancient Rome required
0:29:25 > 0:29:28up to a billion litres of clean water every day.
0:29:29 > 0:29:35All this water got here courtesy of Rome's finest engineering triumph.
0:29:35 > 0:29:36The aqueduct.
0:29:37 > 0:29:41One of the most iconic structures in the Ancient Roman landscape.
0:29:45 > 0:29:47Above the Spanish Steps
0:29:47 > 0:29:50is one of the ancient city's most spectacular examples.
0:29:51 > 0:29:53But it remains hidden
0:29:53 > 0:29:56from the thousands of tourists who come here every day.
0:29:57 > 0:30:00Now, when you said we were going to an aqueduct,
0:30:00 > 0:30:03- I, obviously, was picturing something...- Up on arches.
0:30:03 > 0:30:04Exactly that.
0:30:04 > 0:30:08- I'm now beginning to get a hunch that we're going...- Underground.
0:30:08 > 0:30:11- ..underground!- Underground. - Is that right?
0:30:11 > 0:30:13In fact, we're looking for the entrance
0:30:13 > 0:30:15and it should be coming up...
0:30:15 > 0:30:16Here we are.
0:30:16 > 0:30:18- 2B.- 2B.
0:30:18 > 0:30:21- Should have brought a bottle, or something.- Do you want to knock?
0:30:25 > 0:30:28- Ciao, Adriano.- Hello. How are you? - This is Xander.
0:30:28 > 0:30:30- How do you do? Alexander.- Ciao.
0:30:30 > 0:30:35'Our guide is underground archaeologist Adriano Morabito.'
0:30:35 > 0:30:38- So, Adriano, where are you taking us? All the way...- Whoa!
0:30:38 > 0:30:42- 24 metres down.- OK. - To the Virgin Aqueduct.
0:30:43 > 0:30:47This wonderful spiral staircase is one of the few access points
0:30:47 > 0:30:50to an aqueduct that's hidden beneath the city.
0:30:54 > 0:30:56There it is. Look at that.
0:30:57 > 0:31:01- Crystal clear, Adriano. Virginal, you might say.- Exactly.
0:31:01 > 0:31:05And if you think about it, if you go that way, back to the source,
0:31:05 > 0:31:09it's something like 20km of this aqueduct tunnel.
0:31:09 > 0:31:13But that's just phenomenal engineering, isn't it? How...?
0:31:13 > 0:31:18And think that all the other aqueducts are much longer.
0:31:18 > 0:31:22- Some of these are going up to 90km. - Seriously?
0:31:22 > 0:31:25RUMBLING That's the train. Can you feel it?
0:31:25 > 0:31:28- This is the metro line. - It's the metro line.- Wow.- Wow.
0:31:30 > 0:31:34The Aqua Virgo was built before the birth of Christ.
0:31:34 > 0:31:38It's the only Ancient Roman aqueduct still in use today.
0:31:43 > 0:31:45Oh, Michael, it's freezing.
0:31:45 > 0:31:47HE SPLUTTERS
0:31:47 > 0:31:50- No, it's lovely.- Is it nice? - What about that?!
0:31:50 > 0:31:52- Is it cold? - Clean, fresh and pure and virginal.
0:31:52 > 0:31:54Amazing.
0:32:12 > 0:32:17So, Adriano, this is one of how many aqueducts coming in?
0:32:17 > 0:32:20- There were 11 imperial aqueducts... - Yeah.
0:32:20 > 0:32:23..built during 500 years,
0:32:23 > 0:32:28from 315 BC to 226 AD.
0:32:28 > 0:32:32- And they were built with the town growing.- Yeah.
0:32:32 > 0:32:36So, obviously, they needed more water for more people.
0:32:36 > 0:32:41- And the more water was helping the town to grow at the same time.- OK.
0:32:41 > 0:32:45- So, one fed the other and it was a virtuous circle, then?- Exactly.
0:32:45 > 0:32:48How many of those aqueducts were underground?
0:32:48 > 0:32:52- All of them run, for a certain part, underground.- Right.
0:32:52 > 0:32:56And this particular one, the Vergine, is 99% underground.
0:32:56 > 0:32:58This is 99% underground.
0:32:58 > 0:32:59It was coming out of the ground
0:32:59 > 0:33:02only basically when it was arriving in town,
0:33:02 > 0:33:05- just a few hundred metres after here.- Yeah.
0:33:08 > 0:33:13'And all the water is held in place by an old friend.
0:33:13 > 0:33:16'The pozzolana in the waterproof Roman cement.'
0:33:17 > 0:33:22This is just such a fluke chance that you have in your volcanic soil
0:33:22 > 0:33:26the presence of these oxides that gives it this fantastic quality.
0:33:26 > 0:33:29I mean, that's just a gift from the gods.
0:33:30 > 0:33:33It's a jaw-dropping engineering achievement
0:33:33 > 0:33:35hidden away underneath the city.
0:33:37 > 0:33:39And all powered by gravity.
0:33:39 > 0:33:45Along its 20km length, the aqueduct drops just four metres.
0:33:45 > 0:33:48So, I mean, think about these aqueducts like arteries,
0:33:48 > 0:33:51that are bringing, if you like, the lifeblood into the city of Rome.
0:33:51 > 0:33:53They're bringing not just the drinking water
0:33:53 > 0:33:56but the water that was used for their baths
0:33:56 > 0:33:57and for all the public fountains,
0:33:57 > 0:34:00and everything that made Rome tick
0:34:00 > 0:34:03is coming along these passageways, these pathways.
0:34:05 > 0:34:09The Virgo Aqueduct still feeds the spectacular Trevi Fountain.
0:34:13 > 0:34:15Its route to its source...
0:34:16 > 0:34:19..takes it north past our spiral staircase...
0:34:21 > 0:34:24..then east for another 19km into the hills.
0:34:26 > 0:34:30It's all part of the underground network of 11 aqueducts
0:34:30 > 0:34:33that quenched the thirst of one million toiling Romans.
0:34:40 > 0:34:44But it also supplied water for another essential of Roman life.
0:34:44 > 0:34:45The baths.
0:34:49 > 0:34:51And they, too, had a secret underground life.
0:34:55 > 0:34:58Michael is taking me to the remains
0:34:58 > 0:35:00of one of the 900 available in the city.
0:35:02 > 0:35:03The Caracalla baths,
0:35:03 > 0:35:07named after one of the more obscure Roman emperors,
0:35:07 > 0:35:10is a world away from my modest tub.
0:35:11 > 0:35:15I mean, stating the bleeding obvious. They are massive.
0:35:15 > 0:35:17But look at it. I mean, look at this.
0:35:17 > 0:35:19Do you want to know where we are right now in the baths complex?
0:35:19 > 0:35:21Um, no... Yes, I do. I do!
0:35:21 > 0:35:24- No, I don't, I have absolutely no interest(!)- OK.
0:35:24 > 0:35:27We have just emerged into the hot room.
0:35:27 > 0:35:29- The caldarium.- Imagine it... - Which was a round... I see.
0:35:29 > 0:35:32All of this was part of the original fabric.
0:35:32 > 0:35:34We're standing in the hottest part of it.
0:35:34 > 0:35:37Right under here is where they're going to be having to create all that heat
0:35:37 > 0:35:40to feed the hot room, the caldarium.
0:35:41 > 0:35:46This place also contained warm and cold rooms, a swimming pool,
0:35:46 > 0:35:49two massive gymnasia and libraries,
0:35:49 > 0:35:51and even its own bakery.
0:35:51 > 0:35:55It also had some of the classical world's finest works of art.
0:35:57 > 0:35:59- So, who could come here? - Well, I mean, the numbers are huge.
0:35:59 > 0:36:02Something like 10,000 people.
0:36:02 > 0:36:04This was a baths that could serve
0:36:04 > 0:36:07pretty much most stratas of Roman society.
0:36:07 > 0:36:09So, if you were an Ancient Roman walking along
0:36:09 > 0:36:12through this network of marble-adorned rooms,
0:36:12 > 0:36:15you must just have thought you were it.
0:36:17 > 0:36:20While Michael heads down to explore the underground secrets
0:36:20 > 0:36:23that supported the luxury of the baths above,
0:36:23 > 0:36:26I'm bunking off to indulge myself in a bit of that pampering.
0:36:36 > 0:36:39'Dr Mark Bradley is an expert in Roman hygiene.
0:36:42 > 0:36:46'We're going to enjoy a luxury Roman spa together.'
0:36:46 > 0:36:50Every Roman would attend the bathhouse on a daily basis.
0:36:50 > 0:36:51Very democratic.
0:36:51 > 0:36:55You come in here naked, you know, so without all your trappings.
0:36:55 > 0:36:59This is something that everybody could participate in.
0:36:59 > 0:37:03Take off your fine toga, you take off your purple stripes,
0:37:03 > 0:37:05and you put them aside and everybody is the same.
0:37:05 > 0:37:09But I suppose that maybe things did occasionally stray.
0:37:09 > 0:37:10Any evidence of that?
0:37:10 > 0:37:12In fact, a lot of the writers who write about baths
0:37:12 > 0:37:15focus not on the democratic nature of the baths
0:37:15 > 0:37:18or on the technical ingenuity of baths,
0:37:18 > 0:37:21but on all the really bad things that went on in baths.
0:37:21 > 0:37:24- Go on, Mark, tell us.- We're talking political conspiracies,
0:37:24 > 0:37:28we're talking...orgies.
0:37:28 > 0:37:30Orgies. Now we're getting there. I see.
0:37:30 > 0:37:32Well, I mean, it would happen, you know,
0:37:32 > 0:37:35- in the sultry atmosphere of a... - Yes.- ..of a caldarium.
0:37:35 > 0:37:38- Maybe not the caldarium. Maybe the tepidarium.- Maybe the tepidarium.
0:37:38 > 0:37:39Yeah, yeah.
0:37:43 > 0:37:46The baths experience concluded with a massage.
0:37:46 > 0:37:50It involved lots of pummelling and scraping with a strigil.
0:37:50 > 0:37:52Before soap was invented,
0:37:52 > 0:37:55it was an effective way of removing sweat and dirt.
0:37:56 > 0:38:00For the Romans, daily bathing helped set them apart from the barbarians.
0:38:03 > 0:38:06- It looks a little bit like a scene from a torture chamber.- Just a bit.
0:38:06 > 0:38:10But all these things are designed to sculpt and polish your body.
0:38:10 > 0:38:12Extraordinary level.
0:38:12 > 0:38:16I mean, right down to cell level, really, of cleanliness.
0:38:16 > 0:38:18The Romans must have found it almost unbearable
0:38:18 > 0:38:21to come into contact with any other race.
0:38:21 > 0:38:25- I mean, it must have been a real challenge to their senses.- Yeah.
0:38:25 > 0:38:29But this is exactly how, as a Roman, you differentiate yourself
0:38:29 > 0:38:32from people who don't engage in this cleansing process.
0:38:36 > 0:38:39Um... Walnuts. What are they for?
0:38:39 > 0:38:42These are not there to nibble on if you get peckish.
0:38:42 > 0:38:46So, this would be heated to a very high temperature.
0:38:46 > 0:38:50And then they would be placed on your forearms or your legs
0:38:50 > 0:38:53where you wanted to singe the hairs away
0:38:53 > 0:38:56to make your skin smooth and pliant.
0:38:59 > 0:39:03'But all this luxurious pampering came at a price.'
0:39:03 > 0:39:04Wow!
0:39:04 > 0:39:09Michael's exploring the powerhouse of the Caracalla baths
0:39:09 > 0:39:12with our underground expert, Adriano.
0:39:12 > 0:39:16And this is as massive and as big as what is above ground.
0:39:16 > 0:39:18MICHAEL LAUGHS
0:39:18 > 0:39:19It's incredible.
0:39:19 > 0:39:23It feels like we're in a kind of roundabout.
0:39:23 > 0:39:25It's exactly what it is.
0:39:25 > 0:39:28It was the roundabout at the main entrance
0:39:28 > 0:39:32to control everything that was delivered here.
0:39:32 > 0:39:36- So, what kind of things would have been coming here?- Mainly wood.
0:39:36 > 0:39:38- Ten tonnes of wood per day.- Wow.
0:39:40 > 0:39:43All that wood fuelled a battery of furnaces,
0:39:43 > 0:39:45serviced by an underground army.
0:39:47 > 0:39:52These were the stairs to one of the places where the fire was made.
0:39:52 > 0:39:56We are just below the pools of the caldarium.
0:39:56 > 0:40:01There were 49 ovens all around underground.
0:40:01 > 0:40:06And on these steps, thousands of slaves walked up and down
0:40:06 > 0:40:10bringing wood and a lot of heat.
0:40:12 > 0:40:16There were thousands of slaves working here every day.
0:40:16 > 0:40:18It was really something very close to hell.
0:40:20 > 0:40:24Around a third of Rome's one million residents were slaves.
0:40:24 > 0:40:28In a preindustrial era, it was an efficient,
0:40:28 > 0:40:31if utterly brutal way of organising the economy.
0:40:31 > 0:40:35Caracalla was a microcosm of Rome itself.
0:40:35 > 0:40:42It was an underground city that made what was above ground work.
0:40:42 > 0:40:47Because without this running, we would have not had the baths on top.
0:40:51 > 0:40:54'Even though built on the shoulders of slaves,
0:40:54 > 0:40:58'the baths were still one of the pillars of Roman civilisation.'
0:40:58 > 0:41:02It represents a sort of bookmark in our evolution, really, doesn't it?
0:41:02 > 0:41:06I mean, this is certainly where cleanliness, and thereby health...
0:41:06 > 0:41:10- Yeah.- ..becomes a feature of daily lives.- That's definitely right.
0:41:10 > 0:41:14So, just like aqueducts... and sewers,
0:41:14 > 0:41:17every Roman colony, every part of the empire,
0:41:17 > 0:41:19was expected to have a bathhouse.
0:41:19 > 0:41:22This is something... This is Roman civilisation.
0:41:22 > 0:41:26- And look at it. It's lovely. - It is. It is indeed.
0:41:28 > 0:41:30All this luxury
0:41:30 > 0:41:34powered by an invisible subterranean world of slaves and furnaces,
0:41:34 > 0:41:40connected by 6km of corridors on three separate levels.
0:41:40 > 0:41:44One for the furnaces, another for the water
0:41:44 > 0:41:46and a third for the sewage.
0:41:51 > 0:41:54In a metropolis with up to 900 public baths,
0:41:54 > 0:41:59and a million people, all that waste had to go somewhere.
0:41:59 > 0:42:02And nowhere was there more of a sewage problem
0:42:02 > 0:42:05than the centre of Roman public life, the Forum.
0:42:07 > 0:42:09Originally Rome's marketplace,
0:42:09 > 0:42:13it became one of the most famous meeting places in history.
0:42:13 > 0:42:17To clean up the Forum, the Romans built the Cloaca Maxima,
0:42:17 > 0:42:20the big drain, right underneath it.
0:42:22 > 0:42:26And, I'm afraid, that's where we're heading next.
0:42:27 > 0:42:30I've never been in a sewer before. I hear it's great.
0:42:32 > 0:42:35The rules are, don't touch your face with the outer layer of gloves.
0:42:35 > 0:42:37Take that off, use the inner layer
0:42:37 > 0:42:39if you need to touch your face or anything like that.
0:42:39 > 0:42:42Yeah, I'm rather intrigued.
0:42:42 > 0:42:44Little bit more scared of what lies ahead.
0:42:46 > 0:42:49A lot of instructions about how to touch my face
0:42:49 > 0:42:51or avoid touching my face,
0:42:51 > 0:42:54what I have to remove if I want to touch my face.
0:42:54 > 0:42:56I won't be touching my face.
0:42:56 > 0:42:57'This is probably the oldest
0:42:57 > 0:43:00'continuously working sewer in the world.
0:43:00 > 0:43:04'That's 2,500 years of excrement.'
0:43:04 > 0:43:06I can smell it's a sewer.
0:43:06 > 0:43:08Down I go into the underworld.
0:43:08 > 0:43:10OK.
0:43:12 > 0:43:15Down we go. It's... Blimey, look at this.
0:43:15 > 0:43:17Wow, I wasn't expecting this at all.
0:43:17 > 0:43:20Good Lord! It's huge.
0:43:27 > 0:43:31I mean, it's absolutely staggering, the majesty of this.
0:43:31 > 0:43:33There's a famous story that it was big enough
0:43:33 > 0:43:35for you to drive a cart down full of hay.
0:43:35 > 0:43:39The monumentality is simply breathtaking.
0:43:39 > 0:43:43'Part of the sewer even has a base made from travertine marble.
0:43:43 > 0:43:46'I've seen worse kitchen floors.'
0:43:46 > 0:43:50Here, look at these colossal great blocks of basalt,
0:43:50 > 0:43:52beautiful high vaulting.
0:43:52 > 0:43:56But just to complete the slightly Halloween aspect of it down here,
0:43:56 > 0:44:00see how these curious sort of festoons of who knows what
0:44:00 > 0:44:03have obligingly gathered just to add to the atmosphere.
0:44:03 > 0:44:07And the way the stones are bleached with millennia of stuff
0:44:07 > 0:44:11- that I really don't want to know... - Let's leave it at "stuff".- Yeah!
0:44:14 > 0:44:17It's every bit as unpleasant as the aqueduct was pleasant.
0:44:19 > 0:44:21We're helping the archaeologists working here
0:44:21 > 0:44:25to map the oldest section of this enclosed sewer.
0:44:25 > 0:44:28These vaulted ceilings date from around 600 BC.
0:44:30 > 0:44:34London didn't get a proper sewage system until the Victorian era.
0:44:34 > 0:44:38The Romans engineered this 2,500 years earlier.
0:44:42 > 0:44:44So, Xander, come and have a look at this.
0:44:44 > 0:44:46This is an absolute privilege to see this.
0:44:46 > 0:44:51This layer, this is our cement, our pozzolana, making this waterproof.
0:44:51 > 0:44:54- But can you see that emerging just behind it?- What is it?
0:44:54 > 0:44:58That was a wooden stake, part of the support system
0:44:58 > 0:45:01for when they put up this waterproof cement wall.
0:45:01 > 0:45:05- That piece of wood, that's 2,000 years old.- Look at that.
0:45:05 > 0:45:09Pozzolana still doing its job. Amazing to see down here.
0:45:12 > 0:45:17As the city expanded, so did its invisible world of reeking tunnels.
0:45:17 > 0:45:20Each of them, including the Cloaca Maxima,
0:45:20 > 0:45:22drained into the River Tiber.
0:45:25 > 0:45:29The map also reveals more invisible Roman genius.
0:45:29 > 0:45:32The sewers were part of an integrated network
0:45:32 > 0:45:34of arteries and veins.
0:45:34 > 0:45:36The aqueducts connected to the baths
0:45:36 > 0:45:39and both then connected to the sewers.
0:45:40 > 0:45:43They'd use the overflows from the aqueducts
0:45:43 > 0:45:46to flow into the drain and across the streets in Rome
0:45:46 > 0:45:50to push all the crap that was on the streets into the drain system
0:45:50 > 0:45:52to get it back out to the Tiber again.
0:45:54 > 0:45:56And that wasn't all.
0:45:56 > 0:45:59This sewer was designed to deal with much more than effluent.
0:46:00 > 0:46:04The area of land here, this is marshy, this is below sea level.
0:46:04 > 0:46:05It floods lots.
0:46:05 > 0:46:07So, this thing was constructed
0:46:07 > 0:46:10right from the very beginning in the sixth century BC
0:46:10 > 0:46:13to be big enough to take the floodwaters from the Tiber
0:46:13 > 0:46:17when the water levels rose, so that Rome didn't flood.
0:46:17 > 0:46:18That's extraordinary.
0:46:18 > 0:46:21That helped reduce the number of mosquitoes that were around
0:46:21 > 0:46:23and, as a result, the amount of malaria that was around.
0:46:23 > 0:46:27So, this space, you know, disgusting and terrible as it is,
0:46:27 > 0:46:31really is one of the absolute pillars on which Rome was built.
0:46:31 > 0:46:35But you've got over a million inhabitants, Rome at its peak.
0:46:35 > 0:46:41- That's a lot of poo.- Yeah. 50,000 kilograms of excrement a day.
0:46:41 > 0:46:44- Good God.- But the funny thing is,
0:46:44 > 0:46:47the one thing that this drain might not have been dealing with
0:46:47 > 0:46:51in as much quantity as you might expect is pee, urine.
0:46:51 > 0:46:52They were harvesting that stuff
0:46:52 > 0:46:57and using it as laundry detergent in the city's laundries.
0:46:57 > 0:46:59Marvellous.
0:46:59 > 0:47:00'You think that's marvellous,
0:47:00 > 0:47:03'the Romans even cleaned their teeth with urine.
0:47:03 > 0:47:04'Mouthwatering.'
0:47:07 > 0:47:11Well, I feel I really am truly in the viscera of Rome.
0:47:11 > 0:47:16There's even a waterfall down there. It's pure slurry coming down.
0:47:16 > 0:47:18You just don't want to look too carefully
0:47:18 > 0:47:20where you're putting your feet.
0:47:24 > 0:47:28Going down into the sewer has been quite an eye-opener.
0:47:28 > 0:47:31Something I certainly won't forget in a hurry.
0:47:31 > 0:47:35A horrific experience being down there, but that whole idea
0:47:35 > 0:47:40that they built it so big so early on in Rome's history,
0:47:40 > 0:47:44because it was going to be a way of taking the surge waters of the Tiber
0:47:44 > 0:47:49and thus keeping the land of the Forum and central Rome from flooding,
0:47:49 > 0:47:54I mean, that kind of foresight really took me by surprise.
0:47:54 > 0:47:56- And architecturally magnificent as well.- Yeah.
0:47:56 > 0:47:58I mean, a very extreme experience, as you say.
0:47:58 > 0:48:01And, actually, once you've got the smell of it out of your nostrils...
0:48:01 > 0:48:03- It took a while.- Yeah.
0:48:03 > 0:48:06- I wondered why people were avoiding us in the streets of Rome.- Yeah.
0:48:06 > 0:48:10- And still, you'll notice. - You're not avoiding me, are you?
0:48:10 > 0:48:14Well, I'm not. Contractually, I can't!
0:48:14 > 0:48:17No, but I think as an experience, it was way off the scale.
0:48:17 > 0:48:19It was like visiting the underworld, it really was.
0:48:29 > 0:48:33Our descent into invisible Rome has given me a unique insight
0:48:33 > 0:48:37into how the Romans built and organised their metropolis.
0:48:37 > 0:48:40But the underworld can also reveal things
0:48:40 > 0:48:42about the spiritual life of the Eternal City.
0:48:44 > 0:48:49This place has been the crucible of Christianity for over 2,000 years.
0:48:49 > 0:48:53The evidence is everywhere on the surface.
0:48:58 > 0:49:01But in the grounds of the Barberini Palace,
0:49:01 > 0:49:04underneath the Italian Army's Officers' Club,
0:49:04 > 0:49:07there's evidence of a mysterious religious cult
0:49:07 > 0:49:09that once rivalled Christianity.
0:49:11 > 0:49:13All its temples were built underground,
0:49:13 > 0:49:17a symbol of the cave at the centre of the cult's founding myth.
0:49:18 > 0:49:22- So, yes, if we take a right...- OK.
0:49:24 > 0:49:26Ah!
0:49:26 > 0:49:29Wow! That's not what I was expecting at all.
0:49:31 > 0:49:33Welcome to the cult of Mithras.
0:49:35 > 0:49:37Are you about to initiate me?
0:49:39 > 0:49:42How extraordinary. We've come through a...
0:49:42 > 0:49:45I thought this might be a sort of bag check or something.
0:49:47 > 0:49:51'The cult of Mithras disappeared in the fifth century AD.'
0:49:52 > 0:49:55- And this is the altar?- Yeah, absolutely. We can get up close.
0:49:55 > 0:49:58'Frescoes like these are now the best clues we have
0:49:58 > 0:49:59'to what it was all about.'
0:49:59 > 0:50:03- That is Mithras there.- Absolutely. Looking like Superman.
0:50:03 > 0:50:05I bet Superman wishes he had those little sparkly bits
0:50:05 > 0:50:07on the lining of his cape.
0:50:07 > 0:50:09They never thought about it in time.
0:50:09 > 0:50:13- This is the key image, if you like, of this cult, this religion.- I see.
0:50:14 > 0:50:18'Mithras' dress suggests the cult had its origins in the Middle East.
0:50:18 > 0:50:20'And what's perhaps most striking
0:50:20 > 0:50:22'are its similarities to Christianity.'
0:50:22 > 0:50:24I notice up in the top right-hand corner
0:50:24 > 0:50:27there's someone with what appears to be a halo,
0:50:27 > 0:50:30somebody who looks like they've escaped from a Christian image.
0:50:30 > 0:50:31Yeah, there is a lot of overlap.
0:50:31 > 0:50:33People talk about Mithraism and Christianity.
0:50:33 > 0:50:36They're both developing in Rome at around the same time.
0:50:36 > 0:50:38There's a kind of key date
0:50:38 > 0:50:41in the Roman pagan religious world in Mithraism and in Christianity.
0:50:41 > 0:50:44It all overlaps. And that's December 25th.
0:50:44 > 0:50:47December 25th, for the Romans, was the birthday of the sun.
0:50:47 > 0:50:50In Mithraism, the sun had a huge part to play.
0:50:50 > 0:50:55And the early Christian writers are really quite keen to point out
0:50:55 > 0:51:01- that Mithraism is a dubious, devilish copy of Christianity.- I see.
0:51:01 > 0:51:03Close enough for them to be worried.
0:51:05 > 0:51:07Ultimately, Christianity won out.
0:51:07 > 0:51:11But there was a time when Mithraism was hugely popular,
0:51:11 > 0:51:16especially with the soldiers and the poor right across the Roman Empire.
0:51:16 > 0:51:18Another shrine under Rome opera's workshops
0:51:18 > 0:51:22is one of the 35 underground Mithras temples
0:51:22 > 0:51:25that have been found in Rome alone.
0:51:25 > 0:51:28A further 400 are have been uncovered throughout the empire.
0:51:28 > 0:51:32One as far north as Edinburgh.
0:51:32 > 0:51:35Before the triumph of Christianity,
0:51:35 > 0:51:38Mithraism was one of hundreds of Roman cults.
0:51:40 > 0:51:44People talk about the religions of Rome, and that's absolutely crucial,
0:51:44 > 0:51:47because there are tons of gods and it's an open-ended thing, you know.
0:51:47 > 0:51:50So that people could just pick and mix, really?
0:51:50 > 0:51:52Every time the Romans conquered somebody new,
0:51:52 > 0:51:56they sort of invited their gods in, join the Roman party, if you like.
0:51:56 > 0:51:59Rome and Roman religion does a brilliant job
0:51:59 > 0:52:02of just incorporating them all, as long as, at the end of the day,
0:52:02 > 0:52:06the emperor got their ultimate loyalty.
0:52:06 > 0:52:08And do you know what? It's rather like...
0:52:08 > 0:52:11We've looked at the incredible Roman concrete, Roman cement.
0:52:11 > 0:52:13This is a kind of social cement as well,
0:52:13 > 0:52:15that there's rigidity where it's required,
0:52:15 > 0:52:17and flexibility where it's required.
0:52:17 > 0:52:19And here, it's allowing certain freedoms,
0:52:19 > 0:52:21but knowing where the structure needs to be
0:52:21 > 0:52:23to support the weight as well.
0:52:23 > 0:52:25I think that's a really nice way of thinking about it.
0:52:29 > 0:52:31Our journey beneath the ancient metropolis
0:52:31 > 0:52:34has given me a real sense of what it meant to be a Roman.
0:52:38 > 0:52:40From the bread and circuses of the Coliseum
0:52:40 > 0:52:44to the ritualised bathing and the tolerance of different religions
0:52:44 > 0:52:45in its underground temples.
0:52:47 > 0:52:50But for me, invisible Rome would be incomplete
0:52:50 > 0:52:54without exploring its most iconic underground space.
0:52:54 > 0:52:57I've always wanted to visit the catacombs,
0:52:57 > 0:53:00the place where millions of Romans were laid to rest.
0:53:07 > 0:53:09- You want to head straight ahead. - Straight on down.
0:53:11 > 0:53:12Wow.
0:53:14 > 0:53:17So, what we need to do is get along here.
0:53:18 > 0:53:21- THEY CHUCKLE - This is incredible.
0:53:21 > 0:53:24Between Emperor Augustus and Emperor Constantine -
0:53:24 > 0:53:25about three-and-a-half centuries -
0:53:25 > 0:53:31- there would have been between about 10 and 14 million people needing burying.- Right.
0:53:31 > 0:53:33- That's a lot of people to bury. - That is a lot.
0:53:33 > 0:53:35And one of the reasons that you end up
0:53:35 > 0:53:39with such an enormous number of catacombs is simply space.
0:53:39 > 0:53:42And it's one of these things, it's a fantastic reuse of materials.
0:53:42 > 0:53:44So, the quarry that we were in the other day,
0:53:44 > 0:53:46lots of quarries around Rome,
0:53:46 > 0:53:49- excavating, finding the pozzolana to make...- Yeah.
0:53:49 > 0:53:52But when they're done with the quarry, it's just an empty space.
0:53:52 > 0:53:55Oh, so this is also a quarry? I mean, first and foremost a quarry.
0:53:55 > 0:53:57Absolutely, started life as a quarry.
0:53:57 > 0:54:00- So, this is our old friend tufo again.- This is tufo, yeah.
0:54:00 > 0:54:02This is the natural rock on which Rome is built.
0:54:02 > 0:54:05Each of these, obviously, was a sarcophagus, really, wasn't it?
0:54:05 > 0:54:07The body would just have been laid there.
0:54:07 > 0:54:10We can't think of any big coffin like we would nowadays.
0:54:10 > 0:54:11But these were sealed in.
0:54:11 > 0:54:14Yeah, sometimes with a clay bit on the front with a name.
0:54:14 > 0:54:17- And so who exactly was buried here? Sounds a silly question.- No, no, no.
0:54:17 > 0:54:19The story that's normally told, if you say "catacomb",
0:54:19 > 0:54:22you hear "Christian", don't you, Christian catacombs?
0:54:22 > 0:54:25And there were lots and lots of Christians buried in the catacombs,
0:54:25 > 0:54:26but that's not the full story.
0:54:26 > 0:54:29I want to take you somewhere to show you positive proof of that.
0:54:30 > 0:54:32Here...
0:54:34 > 0:54:37- See something pretty special. - This is incredible.
0:54:38 > 0:54:42- Wow. Look at this. This is plaster. - Yeah.- And then decorated.
0:54:42 > 0:54:46- And look at that, the menorah.- Yeah. - So, this is a Jewish catacomb.
0:54:46 > 0:54:49The Jews were using catacombs for burial
0:54:49 > 0:54:50from about the first century AD.
0:54:50 > 0:54:54Yeah, I had no idea that there were Jewish catacombs.
0:54:54 > 0:54:56You think of catacombs very much as Christian.
0:55:00 > 0:55:02But this isn't just a single catacomb.
0:55:02 > 0:55:06It's a whole complex stretching for nearly a kilometre.
0:55:06 > 0:55:09The final challenge for the scanning team.
0:55:14 > 0:55:18The scan reveals how the passages relate to each other.
0:55:19 > 0:55:21It also shows the wonderfully detailed images
0:55:21 > 0:55:24in the more intricately decorated vaults.
0:55:24 > 0:55:28Archaeologists can now study these frescoes in minute detail
0:55:28 > 0:55:30without harming them.
0:55:34 > 0:55:37- Oh, my goodness. Look at that.- Yeah.
0:55:37 > 0:55:39Whoa.
0:55:39 > 0:55:42We've come to what feels like almost the end of the catacombs.
0:55:42 > 0:55:44No, it goes on and on after this as well.
0:55:44 > 0:55:47We've walked for miles and we've come upon this.
0:55:47 > 0:55:51This is a really expensive place to be buried, this one,
0:55:51 > 0:55:54- and beautifully, beautifully decorated.- Staggering.
0:55:54 > 0:55:58Look, there's a pigeon over there, there's peacocks over here.
0:55:58 > 0:56:00Sheep there.
0:56:00 > 0:56:04And then this is probably an athlete being crowned
0:56:04 > 0:56:07with a garland over his head by the lady to his right.
0:56:07 > 0:56:09But incredibly well preserved.
0:56:09 > 0:56:11And all these kinds of images
0:56:11 > 0:56:14we would normally associate much more with Roman pagans,
0:56:14 > 0:56:16- you know, the Romans. - Oh, I see. This is a pagan...
0:56:16 > 0:56:19So, we've seen much more kind of Christian locali,
0:56:19 > 0:56:20we've been into Jewish cubiculums.
0:56:20 > 0:56:24And now we're into a much more pagan space.
0:56:30 > 0:56:34This catacomb is one of 70 known to exist around Rome.
0:56:34 > 0:56:38Their tunnels stretch round the city for miles.
0:56:39 > 0:56:43The final resting place of so many ordinary Romans
0:56:43 > 0:56:46who built and ran this remarkable metropolis.
0:56:46 > 0:56:50A fitting underground space to finish our adventure.
0:56:50 > 0:56:53It's been an incredible privilege, hasn't it,
0:56:53 > 0:56:58to see not just the muscles of Rome, but its arteries, its lungs
0:56:58 > 0:57:00and its intestines and colon as well!
0:57:00 > 0:57:02And it gives you a real sense
0:57:02 > 0:57:06of just how this city of a million people was able to function.
0:57:06 > 0:57:08I think, also, we've seen
0:57:08 > 0:57:13the extraordinary and complete fluke confluence of circumstances
0:57:13 > 0:57:17that allowed Rome just to make its stance
0:57:17 > 0:57:20and say, right, here we are, we're going to take over the world.
0:57:20 > 0:57:22It's that perfect storm, isn't it,
0:57:22 > 0:57:26the Roman genius that turns that pozzolana into cement and concrete
0:57:26 > 0:57:27that builds the Pantheon,
0:57:27 > 0:57:30that pushes the boundaries of what's possible with architecture
0:57:30 > 0:57:35and create spaces and places on a scale never dreamed before.
0:57:39 > 0:57:42All of this came out of invisible Rome.
0:57:47 > 0:57:51The honeycombs of quarries that made Rome's building revolution.
0:57:51 > 0:57:55The aqueducts and sewers that supplied and cleansed it.
0:57:57 > 0:58:00The spaces that nurtured it spiritually.
0:58:00 > 0:58:03And, finally, the places that received its dead.
0:58:18 > 0:58:21Our journey through invisible Rome has opened my eyes
0:58:21 > 0:58:25to so many new secrets in this, my favourite city.
0:58:27 > 0:58:29I won't be going back down that sewer in a hurry, though.