0:00:27 > 0:00:30Sprawling out from the River Liffey,
0:00:30 > 0:00:33Dublin is home to more than a million people.
0:00:33 > 0:00:38That's over a quarter of the Republic's total population.
0:00:38 > 0:00:43It was the Liffey and its link to the open sea that brought Dublin its prosperity.
0:00:45 > 0:00:48This is Dublin's Great South Wall,
0:00:48 > 0:00:50built nearly 300 years ago
0:00:50 > 0:00:53to protect ships sailing into the River Liffey.
0:00:53 > 0:00:58On the far side of the estuary is the Bull Wall, added a century later
0:00:58 > 0:01:02and designed to stop the sands of Dublin Bay choking the river.
0:01:03 > 0:01:08Almost two-thirds of the Republic of Ireland's sea trade moves through Dublin.
0:01:08 > 0:01:14These two massive walls are still vital in keeping the seaway open.
0:01:16 > 0:01:20Between them, the deep shipping channel remains open at all tides,
0:01:20 > 0:01:24while the beaches on either side are dried out twice a day.
0:01:24 > 0:01:29The sands stretch the full sweep of Dublin Bay.
0:01:37 > 0:01:39I'd never been here before,
0:01:39 > 0:01:45but Dublin writer Fionn Davenport revels in his city's secret riviera.
0:01:48 > 0:01:52I never pictured Dublin like this, with a great huge beach.
0:01:52 > 0:01:5615 miles of beaches stretching from the north, down to the very south.
0:01:56 > 0:01:57It's great, isn't it?
0:01:57 > 0:02:03I'm ashamed to say that when I hear the word "Dublin", I just think, you know, pubs and pints and Guinness.
0:02:03 > 0:02:08This is exactly how we sell ourselves. This is the great secret of Dublin - our beaches.
0:02:08 > 0:02:10We don't talk about them, don't tell anybody about them,
0:02:10 > 0:02:13and we keep them exactly the way we want them - empty.
0:02:16 > 0:02:21The Irish are known for their hospitality, whether their visitors are invited or not.
0:02:25 > 0:02:27Nowhere more so than Dublin.
0:02:27 > 0:02:32In fact, historically, this city has scarcely been Irish at all.
0:02:32 > 0:02:37The history of Dublin is the history of invaders.
0:02:37 > 0:02:41Right from the very, very start, it was created by invaders,
0:02:41 > 0:02:44populated by invaders, so in a sense, Dublin is an invader city.
0:02:44 > 0:02:47Who were the first people to settle here?
0:02:47 > 0:02:50Oh, the Vikings, in the 9th century.
0:02:50 > 0:02:53They came here on their raping, pillaging, warring ways,
0:02:53 > 0:02:56and they settled, and built this trading port.
0:02:56 > 0:03:00The name Dublin comes from the Irish "Dubh Linn",
0:03:00 > 0:03:04and the original Viking settlement was built around this black pool.
0:03:04 > 0:03:09- That's where the word comes from - "dubh" meaning black, "linn", the pool.- Blackpool?- Yes.
0:03:09 > 0:03:13- I was hoping for something Gaelic and lyrical like "shining city by the sea."- I know.
0:03:13 > 0:03:17A Viking Blackpool - that's a scary thought.
0:03:22 > 0:03:25Then, in the 1100s,
0:03:25 > 0:03:29another wave of invaders flooded up the Liffey - the Normans.
0:03:29 > 0:03:33They and their English successors would stick around for 800 years,
0:03:33 > 0:03:36long enough to make a mark.
0:03:39 > 0:03:42Dublin's best-known brewery, Guinness,
0:03:42 > 0:03:46was founded by an Anglo-Norman family,
0:03:46 > 0:03:52and Dublin architecture still reflects the longstanding link across the water.
0:03:52 > 0:03:56In Ireland's capital city, what is Britannia doing on top of that building?
0:03:56 > 0:04:01Ah, Neil, because secretly, Dublin is still a little bit British. It's a very English city.
0:04:01 > 0:04:03800-odd years of English rule -
0:04:03 > 0:04:09Dublin was created, conceived of, developed and built by the English,
0:04:09 > 0:04:11and this building behind us is the Custom House,
0:04:11 > 0:04:15which was built when this was the second city of the British Empire.
0:04:15 > 0:04:20I would have to dispute that as a Scot. We were always told Glasgow was the second city of the Empire.
0:04:20 > 0:04:23But the tragedy of the Scots is they were lied to for so long,
0:04:23 > 0:04:26because Dublin was the second city of the Empire.
0:04:31 > 0:04:36Today, Dublin takes second place to no-one.
0:04:36 > 0:04:40Glass and steel has transformed the old waterfront.
0:04:40 > 0:04:43It's Dubliners who are flooding to the Liffey now.
0:04:49 > 0:04:52The quickest way out of Dublin isn't by boat
0:04:52 > 0:04:57but by DART, the fast rail corridor that hugs the shoreline of Dublin Bay.
0:05:05 > 0:05:09The DART has made these once sleepy coastal suburbs
0:05:09 > 0:05:12much more accessible to commuters, but ironically,
0:05:12 > 0:05:16locals will tell you that today owning a seafront property
0:05:16 > 0:05:18is beyond the reach of most Dubliners.
0:05:26 > 0:05:32Unlike Britain, Ireland gives artists and entertainers generous tax breaks.
0:05:32 > 0:05:37For these glitterati, Howth Head has become an exclusive address,
0:05:37 > 0:05:41with properties changing hands for over £5m.
0:05:43 > 0:05:48I'm Dave Kelly, and I sell spectacular seaside homes to the rich and famous.
0:05:48 > 0:05:53Welcome to one of Ireland's most exclusive residential addresses - Sutton Castle.
0:05:55 > 0:06:01This house was commissioned in the 1890s by the grandson of John Jameson of the famous Irish whiskey brand,
0:06:01 > 0:06:05and it's recently been converted into luxury apartments.
0:06:05 > 0:06:09It's as close to the sea as you can get without getting your feet wet.
0:06:11 > 0:06:16A sea view can easily add tens of thousands of Euros to the value of a property.
0:06:16 > 0:06:19And for an apartment in this particular complex,
0:06:19 > 0:06:23it can set you back anything up to 3 million euros, or 2 million sterling.
0:06:37 > 0:06:40We've reached the River Boyne -
0:06:40 > 0:06:45not just a waterway, more an artery leading to the ancient heart of Ireland.
0:06:54 > 0:06:56It's so peaceful here today.
0:06:56 > 0:07:02There's just me and some day-trippers, and the only sounds are from the sea.
0:07:02 > 0:07:07It's hard to believe that so much of Ireland's history has happened around this one river.
0:07:07 > 0:07:12For 5,000 years, since the first Neolithic farmers,
0:07:12 > 0:07:18the mouth of the Boyne has been the gateway to Ireland's fertile heartland.
0:07:18 > 0:07:24It's been navigated by Celtic traders, Viking raiders and Norman invaders.
0:07:30 > 0:07:34Striding north, the flat coastal plains of the Irish midlands
0:07:34 > 0:07:38give way to the mountains of Northern Ireland.
0:07:43 > 0:07:45But in this border country,
0:07:45 > 0:07:50a landscape much older than any national frontier divides Ireland.
0:07:52 > 0:07:5660 million years ago, as the dinosaurs were dying out,
0:07:56 > 0:08:00the Earth's crust stretched and fractured here.
0:08:00 > 0:08:05Explosive volcanoes erupted, and mountains were thrown skywards.
0:08:05 > 0:08:10Its legacy is the rugged shoreline around Carlingford Lough.
0:08:15 > 0:08:18On the far side of the lough is Northern Ireland,
0:08:18 > 0:08:21but I'm still in the south, and it's a Euro zone.
0:08:21 > 0:08:25But this close to the border, the Euro and sterling co-exist,
0:08:25 > 0:08:28and for a few, that presents a lucrative opportunity
0:08:28 > 0:08:30to exploit the difference.
0:08:33 > 0:08:35Why's it so busy?
0:08:35 > 0:08:39- Well, I suppose because it's cheaper. - How much cheaper?
0:08:39 > 0:08:44Er... Approximately 20% cheaper on both petrol and diesel.
0:08:44 > 0:08:47So if you were filling up a typical car, what's the saving?
0:08:47 > 0:08:49Approximately £12 sterling.
0:08:49 > 0:08:51- That's a brilliant saving.- Yep.
0:08:51 > 0:08:54Where exactly is the border?
0:08:54 > 0:08:58- I challenge you to find it. - You're on!
0:08:58 > 0:09:04And he was right - despite having different capitals, different laws and different currencies,
0:09:04 > 0:09:08the border between North and South has vanished altogether.
0:09:08 > 0:09:12The first sign that you're in the North is the one in miles per hour.
0:09:17 > 0:09:20Nature makes a better fist of a frontier.
0:09:20 > 0:09:25The massive granite buttress of the Mourne Mountains is a formidable obstacle.
0:09:43 > 0:09:48Last time, we came here to discover how Belfast built Titanic.
0:09:48 > 0:09:53This time, we're on a mission to uncover who built Belfast.
0:09:57 > 0:10:02Belfast is the most industrial city in Ireland.
0:10:02 > 0:10:04It defies nature that it's here at all.
0:10:09 > 0:10:13Like Dublin, Belfast grew up around a tidal river -
0:10:13 > 0:10:16the Lagan.
0:10:16 > 0:10:20The original site was a ford, just where the river is spanned by these bridges.
0:10:22 > 0:10:26Close by, they're building a 29-storey skyscraper.
0:10:28 > 0:10:32Drilling for the foundations reveals just how much of Belfast
0:10:32 > 0:10:35is built on mud and salt water.
0:10:36 > 0:10:38That's the stuff they call sleetch!
0:10:38 > 0:10:41I think you and I would call it filthy stinking muck.
0:10:41 > 0:10:44In a funny way, it smells a bit like the sea.
0:10:44 > 0:10:47It's got that pungent smell about it, like seaweed,
0:10:47 > 0:10:51but seaweed that's been trapped underground for a long, long time.
0:10:51 > 0:10:56But the point is, all of Belfast is built on top of that.
0:10:56 > 0:11:03Kerry Greeves, the project engineer, is tackling the same problems as Belfast's original builders.
0:11:04 > 0:11:08- The bedrock, which is sandstone, is about 50 metres down.- 50?- Yes.
0:11:08 > 0:11:11We have to use piles, which are going down on this side
0:11:11 > 0:11:15approximately 28 metres, and that's what will hold up the building.
0:11:15 > 0:11:17So the piles don't reach the rock?
0:11:17 > 0:11:22- No.- So the building is just floating on...mud?
0:11:22 > 0:11:24Well, you could say that.
0:11:24 > 0:11:28As an engineer, it's slightly more technical than that, but effectively yes.
0:11:28 > 0:11:32Belfast's founding fathers floated their dream here on the shoreline.
0:11:32 > 0:11:39Local author Glenn Patterson has summed up their achievement with these lines.
0:11:41 > 0:11:44"Belfast is a triumph over mud and water,
0:11:44 > 0:11:49"the dream of successive generations of merchants, engineers and entrepreneurs,
0:11:49 > 0:11:54"their names driven like screw piles into the city's sense of itself.
0:11:54 > 0:11:58"Dargan, Dunbar, Workman, Harland..."
0:12:02 > 0:12:05The thing is, they're all Scottish or English names,
0:12:05 > 0:12:10Protestant merchants attracted here from the beginning of the 17th century
0:12:10 > 0:12:12by the promise of land at the water's edge.
0:12:12 > 0:12:17I wanted to hear more from the man who celebrated these entrepreneurs.
0:12:18 > 0:12:24A lot of people came here with ideas about settling this place, developing this place.
0:12:24 > 0:12:27Some bloody-minded people, you would have to say.
0:12:27 > 0:12:29This isn't a promising place to make a city.
0:12:29 > 0:12:32Belfast has no business being here at all.
0:12:32 > 0:12:34So what was behind the stubbornness?
0:12:34 > 0:12:37Something must have attracted them and made them stay.
0:12:37 > 0:12:41Belfast, although it's very unpromising, it's got all that muck, that sleetch,
0:12:41 > 0:12:45you had to dig right down and sink your foundations if you wanted to build here,
0:12:45 > 0:12:49you could actually make bricks out of the clay of the city,
0:12:49 > 0:12:52so, in a sense, Belfast is a city that's made of itself.
0:12:59 > 0:13:03Every inch of Belfast's industrial heartland is man-made,
0:13:03 > 0:13:07dredged and reclaimed from the salt-water shore in the 19th century
0:13:07 > 0:13:09to underpin its expansion.
0:13:09 > 0:13:15But to build on that growth, Belfast had to look seawards again - to trade.
0:13:17 > 0:13:24When you look at this vast port, it's almost as though this water matters more than the land.
0:13:24 > 0:13:27Well, certainly without this, without the trade -
0:13:27 > 0:13:31I mean we're sailing past these container ships here -
0:13:31 > 0:13:34without that, Belfast wouldn't have developed in the way that it did,
0:13:34 > 0:13:39and without the port, there wouldn't have been any of those great industries of the 19th century.
0:13:39 > 0:13:42So this city really is defined by this water.
0:13:45 > 0:13:47Belfast, the floating city.
0:13:52 > 0:13:56Subtitles by Red Bee Media Ltd