0:00:10 > 0:00:15It's good to see ourselves as others see us.
0:00:18 > 0:00:2120 miles or so over there is Dover.
0:00:21 > 0:00:25This is the view of our coast from France.
0:00:55 > 0:00:59At Le Havre, a huge gash opens up in the coast.
0:00:59 > 0:01:03This is where the sea meets one of the world's mightiest rivers -
0:01:03 > 0:01:04the Seine.
0:01:06 > 0:01:09A great river demands a great bridge.
0:01:09 > 0:01:12And the Pont de Normandie rises to the occasion.
0:01:13 > 0:01:16Seven years in the making, 184 steel cables
0:01:16 > 0:01:19suspend the road over the river.
0:01:19 > 0:01:23That's the left bank of the River Seine down there.
0:01:23 > 0:01:26Travel about 120 miles in that direction
0:01:26 > 0:01:30and you arrive in the famous artistic district of Paris.
0:01:30 > 0:01:34But there's another little artistic gem on the left bank of the Seine...
0:01:36 > 0:01:41In Honfleur, even the boat builders have an artistic flair.
0:01:43 > 0:01:46Their craft helped see off the English
0:01:46 > 0:01:49during the Hundred Years' War.
0:01:52 > 0:01:56When peace was finally declared, the boat builders of Honfleur
0:01:56 > 0:01:58used their skills to build a church,
0:01:58 > 0:02:00a wooden church.
0:02:03 > 0:02:04Started in the 1460s,
0:02:04 > 0:02:09its roof reflects its maritime heritage,
0:02:09 > 0:02:12looking like the upturned hull of a ship.
0:02:21 > 0:02:25Oddly, the bell tower's built separately,
0:02:25 > 0:02:29maybe to protect the wooden church against lightning strikes,
0:02:29 > 0:02:33or perhaps the vibration of the bells. No-one's quite sure.
0:02:36 > 0:02:39Honfleur's witnessed a steady stream of traffic
0:02:39 > 0:02:42crossing the Channel for centuries.
0:02:43 > 0:02:46But in 1066, thanks to William the Conqueror,
0:02:46 > 0:02:49it was all heading in our direction.
0:02:52 > 0:02:56Invasion came as second nature to these Normans.
0:02:56 > 0:02:58After all, originally they were Norsemen,
0:02:58 > 0:03:02Viking marauders who'd only been in France 150 years
0:03:02 > 0:03:04before they turned their sights on us.
0:03:04 > 0:03:06But they left a permanent legacy...
0:03:06 > 0:03:10in stone.
0:03:10 > 0:03:14The Normans taught us their tradition of castle construction,
0:03:14 > 0:03:16bringing it to Britain.
0:03:16 > 0:03:19Among their first big builds, the Tower of London
0:03:19 > 0:03:21and Canterbury Cathedral.
0:03:21 > 0:03:24And they built them with French stone.
0:03:26 > 0:03:29In the heart of Normandy, Mark Horton's on his way
0:03:29 > 0:03:31to the city of Caen in search of that special stone,
0:03:31 > 0:03:35worthy of William's English castles.
0:03:38 > 0:03:42In the years after 1066,
0:03:42 > 0:03:45the River Orne that connects Caen to the sea
0:03:45 > 0:03:49would have been busy with Norman longboats like this one,
0:03:49 > 0:03:52transporting great blocks of stone to Britain for building.
0:03:52 > 0:03:57Medieval castle expert Pamela Marshall and I are retracing
0:03:57 > 0:04:01the route to try and discover why.
0:04:01 > 0:04:04Caen stone is one of the best,
0:04:04 > 0:04:06and, I know it seems a long way from England,
0:04:06 > 0:04:08but he's got this waterway.
0:04:08 > 0:04:12He then just whips it across the sea, up the Thames,
0:04:12 > 0:04:17and it's a material that his craftsmen are well versed with.
0:04:17 > 0:04:19- They know how to use it. - He presumably thinks
0:04:19 > 0:04:22- the Anglo-Saxon masons are rubbish anyway.- Possibly.
0:04:22 > 0:04:25And remember the Anglo-Saxons aren't used to castles at all,
0:04:25 > 0:04:27let alone stone ones.
0:04:33 > 0:04:38William not only had a might river to transport the stone,
0:04:38 > 0:04:42but at Caen he had a ready supply right beneath his feet.
0:04:44 > 0:04:47The city was built on limestone.
0:04:47 > 0:04:51A rare limestone, containing very few fossils.
0:04:51 > 0:04:55Having used it for castles and cathedrals here,
0:04:55 > 0:04:59William was determined to bring it to England.
0:05:00 > 0:05:03Hidden beneath the streets of modern Caen,
0:05:03 > 0:05:06there's still a labyrinth of ancient stone quarries,
0:05:06 > 0:05:09abandoned since the Middle Ages.
0:05:09 > 0:05:14We've come to one tucked away in a quiet corner of the city.
0:05:14 > 0:05:18It's only accessible, we're told, because the roof collapsed,
0:05:18 > 0:05:20creating a makeshift entrance.
0:05:26 > 0:05:30Inside, it's as if the workers had left yesterday.
0:05:32 > 0:05:34Look at this.
0:05:34 > 0:05:38- That's where the chariot, the wagon...- The wagon has brushed past!
0:05:38 > 0:05:40..has brushed past it.
0:05:40 > 0:05:44- Regardez ici... - Oh, these are fantastic.
0:05:44 > 0:05:48To split the rock away, they cut out a wedge shape with chisels
0:05:48 > 0:05:54and then insert a dry wooden wedge, which they then wet.
0:05:54 > 0:05:58And as the wood expands, it helps the rock to split naturally.
0:05:58 > 0:06:02- That's extraordinary, it's like a frozen moment in time.- Absolutely.
0:06:03 > 0:06:08But what was it about the stone that made it so special?
0:06:10 > 0:06:12Worth hauling across the channel.
0:06:12 > 0:06:16Who better to ask than a group of modern Norman masons?
0:06:17 > 0:06:20Jean Pierre Dauxerre, a former city planner,
0:06:20 > 0:06:24is passionate about Caen stone.
0:06:24 > 0:06:30It's a stone which like to stroke with eyes, with hands.
0:06:30 > 0:06:32Is it possible to break it open?
0:06:32 > 0:06:34Yes, it is.
0:06:37 > 0:06:39Here we go.
0:06:39 > 0:06:41- Deux...- Two.
0:06:44 > 0:06:45Give it some welly!
0:06:45 > 0:06:48- Hey...!- Bravo!
0:06:48 > 0:06:49Et voila.
0:06:49 > 0:06:52- You are strong! - I know, isn't it amazing?
0:06:52 > 0:06:56- Just a few pieces like this and look what happens.- It's your work.
0:06:56 > 0:06:59There are no fossils or anything.
0:06:59 > 0:07:02It's the colour of churches, castles...
0:07:02 > 0:07:08But the stone now is so soft, just falls apart in one's hands.
0:07:08 > 0:07:14Stone becomes hard because water...goes away.
0:07:14 > 0:07:16- Evaporates?- Evaporates, yes.
0:07:18 > 0:07:21The stone is quite soft when extracted.
0:07:21 > 0:07:27Easy to split or cut, using even the most basic tools.
0:07:27 > 0:07:30And the longer it's exposed to the air, the tougher it gets.
0:07:32 > 0:07:34That's completely exhausting!
0:07:34 > 0:07:39And without shells or fossils to make it fracture unpredictably,
0:07:39 > 0:07:42it can also be finely worked.
0:07:42 > 0:07:48Which is why it was highly prized among medieval masons.
0:07:50 > 0:07:53The Normans helped shape Britain.
0:07:53 > 0:07:57They laid the foundations for some of our greatest buildings.
0:07:57 > 0:08:00Although these structures have been extended since,
0:08:00 > 0:08:05there's a little bit of Normandy left in most of them.
0:08:07 > 0:08:10E-mail subtitling@bbc.co.uk