EUROPA (Desmontando las Catedrales Medievales) - Documental
Las catedrales medievales de Inglaterra, que datan de entre aproximadamente 1040 y 1540, son un grupo de veintiséis edificios que constituyen un aspecto importante del patrimonio artístico del país y figuran entre los símbolos materiales más significativos de la cristiandad.
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00:00The great gothic cathedrals of Europe. High medieval skyscrapers that hold ancient secrets.
00:10How did their creators manage to raise them to that height using simple tools?
00:19What beliefs inspired them to rise to the heavens?
00:23It is an incredible building. The height, the floor, the presence is really spectacular.
00:29And can the new technologies unravel the science that protects these ancient stones from disaster?
00:36They had to be afraid that the pressure of the earth would collapse the moats.
00:42The only way to solve these mysteries is to dismantle these impressive medieval megastructures, stone by stone.
00:53Exploring its walls, chambers and foundations will help us to unearth the amazing secrets of engineering hidden in this ancient wonder.
01:11The German city of Cologne, on the banks of the Rhine River.
01:16This is the home of the most ambitious megastructure in the world.
01:25The cathedral of Cologne.
01:27A mysterious monument that began its life in the Middle Ages.
01:32750 years ago, the inhabitants of this city embarked on a colossal challenge to build the tallest cathedral of its time.
01:4320 times taller than the wooden buildings of the city.
01:49The large scale of this church surprises modern experts who try to unveil its secrets.
01:56The amazing thing about the cathedral of Cologne is that at that time someone actually had the vision to design and conceive a building of this size.
02:05And it's spectacular.
02:07The cathedral of Cologne is a giant stone of 120,000 tons.
02:20On its walls there is enough glass to cover a skyscraper of 30 floors.
02:27Immense vaults of crossings support the ceiling and also the roof of 600 tons.
02:40Rising almost 160 meters in the sky, two huge towers once made of this church the tallest building on earth.
02:49But how did they build this medieval wonder?
03:00Historians know surprisingly little about what happened during the first days of the construction of Cologne.
03:08Few documents have survived.
03:11But the architect Doc Pritchard can rediscover how the cathedral was built, separating stone by stone.
03:23Doc has the perfect tool to do it. A digital laser scanner.
03:30This machine will allow him to reveal the building with unprecedented details.
03:36The scanner is really quite incredible. It can generate approximately a million dimension points per second.
03:46The way that the scanner works is that it does a 360 degree sweep.
03:51It will show things like the depth of the vaults, the size of the columns, in a very precise way.
03:58We take all that data together and the result is you have a 3D map of the cathedral.
04:06Today, Doc is going to add another important piece to his puzzle.
04:16He goes to the central balcony.
04:21If he manages to use the scanner to expose the underlying structure of the cathedral, he will be able to start dissecting it.
04:28One of the great advantages of the laser scanner is that it allows you to isolate data, which we can use later to explain the architecture, how the building stood up and how the engineering was done.
04:43Doc's scanner shoots an invisible laser beam up to 187 meters away.
04:50It records each solid element it encounters and bounces.
04:58Then it converts this data into incredibly detailed images, with which Doc will be able to study the structure from all angles.
05:08In total we have done about 660 scans. Probably by the end of this week we will add another 20 or 30.
05:17Doc must process a huge volume of data.
05:21But he is already starting to see the master plan of the people who built this incredible monument.
05:29The two towers can be seen from miles away.
05:38At the top, the needles are open to reduce wind resistance.
05:44And at the bottom, the walls are made of solid rock to withstand the enormous weight of the towers.
05:51But the church below is completely different.
05:55Under the coating there is a skeleton of slender stone arches.
06:00Incredibly, it is very similar to the core of any modern skyscraper.
06:06However, it was the idea of medieval master builders, men who lived 700 years ago.
06:15So how could the citizens of Cologne think of the possibility of building such a tall building?
06:25320 kilometers away, in the north of France, another team is looking for clues in an even older cathedral.
06:36This is the Amiens Cathedral, the anteproject of the one in Cologne.
06:43This very tall church has dominated the city's horizon for almost 800 years.
06:49It is the tallest cathedral in France.
06:55The researcher Guillaume Caron uses laser technology to reveal how the predecessor of Cologne was built.
07:04I was born in this city, so I know the symbolic aspects of this cathedral.
07:11Guillaume hopes to find small clues that can help to reconstruct the original design lost from the cathedral.
07:19Currently there is no real map of the cathedral.
07:25It was not part of the culture of the 13th century, to keep the maps or anything.
07:31So what we are doing with this device is to measure it precisely to make the first map of the cathedral.
07:40The construction of the Amiens Cathedral began in 1220 and is one of the few cathedrals near Paris whose architects dreamed of getting closer to God.
07:54They wanted to build the tallest and widest cathedral because at that time, in the Middle Ages, there was a kind of competition between different cities in France to build the most important cathedral.
08:07Guillaume's scanners reveal that the central arch is 43 meters high, but the columns are surprisingly thin.
08:17From the previous view of the scanner, we can see the details it has captured. For example, the cross-section of the columns.
08:27But in the 12th century, such high and thin columns would have been too weak to support such a large building.
08:35So how did the French architects solve a puzzle that even disconcerted the great builders of ancient Rome?
08:47The key is in the shape of the arches. In a classical Roman arch, the stones at the top press against the columns.
08:57As it is built higher, they begin to give in and the roof collapses.
09:10But the French engineers observed that if they built pointed arches, the forces flowed towards the base of the columns, much more resistant.
09:21Thus, the same columns can bear more weight, the arch can be much higher and the church much larger.
09:31The cathedral of Amiens, with its pointed arches, allowed the citizens of Cologne to glimpse all the possibilities.
09:42But what prompted the Germans to build even higher?
09:48The secret is in the heart of the cathedral of Cologne, inside this sanctuary of gold.
09:56Some believe that it contains the bones of the three wise men.
10:02Peter Fiesenig is the current head architect of the cathedral.
10:07Have you checked the lighting of the vault?
10:12He supervises an army of more than 70 people who keep this building in operation.
10:21Today, the church attracts 6 million visitors a year.
10:27But Peter thinks that in the Middle Ages, this tomb was the star attraction.
10:34The sanctuary is, of course, one of the reasons why the cathedral of Cologne was built, rather because of what it contains.
10:46I mean the bones of the three wise men.
10:50This holy relic arrived in Cologne in 1164 and immediately triggered a great stream of pilgrims.
10:58This meant that the old church began to be too small, so they had to build a larger cathedral.
11:08This mysterious sanctuary inspired the founders of Cologne to start working on a cathedral of such a size that from the beginning they knew they would never see it finished.
11:21This is something that continues to fascinate us today.
11:25The cathedral of Cologne is one of the first multigenerational projects of humanity.
11:32Something that you have to give to the next generation and trust that they will continue to build.
11:41These men hoped that their children and grandchildren could overcome the next great obstacle.
11:47How to build a church with enough space for 20,000 faithful and delicate glass walls?
12:06The cathedral of Cologne is a mysterious medieval skyscraper.
12:11It covers 8,000 square meters.
12:15How did their builders illuminate such a large church with natural light hundreds of years before electricity existed?
12:27The answer is hidden inside the structure of the cathedral.
12:36The towers rest on thick stone pillars that prevent them from collapsing.
12:44But the main vestibule of the church is much more open.
12:50Here there is enough glass to cover a football field.
12:55In its central area, the upper walls are almost entirely made of glass, a few millimeters thick.
13:04And they are crowned by a huge lead ceiling.
13:09So, how did the medieval engineers build such large and fragile windows, but at the same time so strong?
13:19In the Middle Ages, craftsmen had no way of making huge flat sheets of glass.
13:25Ulrike Brinkmann studies the ingenious solution that allowed them to exceed the limits of technology.
13:31The medieval glass makers divided each window into panels.
13:36They made them from small fragments of inked glass, joined together by lead.
13:42In the Middle Ages, glass was blown by hand, with the mouth.
13:48They had a large blowpipe, so the size of the glass panels that were used for the glass panels was limited.
13:56The restorer Peter Bekenkof reveals the craftsmanship used in each individual piece of glass, carefully removing centuries of dirt.
14:08It is a very delicate process, and the conservators must know what they have under their hands, so to speak.
14:16It is necessary to have a lot of experience to be able to do it.
14:20We see some very, very dark deposits on the glass, which, luckily, in this case, can be easily removed.
14:32The fragments remain dark after cleaning, but they come to life under the sun.
14:40In the Middle Ages, light was just one more material.
14:45And how light helped to see another material, like glass, without disturbing the glass, was without any explanation.
14:59These exquisite details were imperceptible to the faithful who came to the cathedral.
15:06But this glass kaleidoscope creates the optical impression that this church reaches the sky.
15:15Entering the cathedral in medieval times must have been impressive.
15:20The sun entering and illuminating the interior must have been spectacular.
15:26It is still impressive today.
15:29Imagine at that time when people lived in small and dark houses.
15:34But the extreme height of these windows poses a serious problem.
15:42The pointed arches allow to build taller and more elegant churches, with large windows from top to bottom.
15:49But if the height was too high, the structure could collapse.
15:54Some support walls, called counterforts, helped to relieve the pressure, but blocked the light.
16:00And cut the side corridors.
16:05The medieval engineers discovered that if they built columns on the outside, with high transverse beams,
16:11they could build what is known as arbotantes.
16:15In this way, they could install huge windows that brought them closer to God, and let in their celestial light.
16:24These counterforts were used by the priests and the clergy.
16:29These counterforts help to support the walls and the ceiling from the outside.
16:35But what prevents the ceiling from falling inside the church?
16:40Why does it seem to hang in the air?
16:49Wolfgang Kupper is one of the 20 experts in the cathedral of Cologne.
16:54He knows that working the soft limestone requires absolute precision.
16:59With this saw blade that I borrowed from the metalworkers, I can easily cut the stone.
17:06The counterforts are like the surgeons who care for a patient of 750 years.
17:12Today, Wolfgang has the challenge of replacing a block of stone called baldaquin.
17:19Now I'm working on this pinnacle.
17:22I have to carve these holes and remove the remaining material to remove these leaves.
17:28These are incredibly small details.
17:31The original stone that was part of the wall is too damaged to be repaired.
17:37It was damaged during the Second World War.
17:40The front part has completely disappeared.
17:43Only the back remains.
17:46Carving this copy will take Wolfgang a year and a half.
17:53It is really exhausting to work on something for so long and to focus on it constantly.
18:00It is something annoying and, of course, small mistakes happen.
18:05Nobody is perfect.
18:08Thanks to the perfection of Wolfgang's medieval predecessors,
18:12the cathedrals still stand.
18:22Instead of thick stone walls that supported the ceiling,
18:26they carved pointed arches and joined them like a thoracic box.
18:30In the middle, they put only a thin layer of bricks that forms a smooth roof called a vault.
18:50The thin columns channel the weight of this vault to the ground.
18:55In this way, the roof does not need support.
18:58The vault is held by itself.
19:04The forces exerted by this vault are enormous.
19:08And some stones out of place could mean disaster.
19:17The old cathedral of Amiens, in France, reveals the risks of this daring design.
19:23The expert in laser scanning, Guillaume Caron, is in Amiens,
19:28investigating the damage caused by the vaults.
19:36We have a big crack on the ceiling that we measure with our laser scanner.
19:43This is the result of the scanning.
19:46Guillaume discovers that the crack is 5 centimeters wide.
19:50There are other cracks inside the main nave of the cathedral.
19:54For example, there is one in the upper part of that window.
19:59Guillaume can not know exactly what is causing each crack.
20:03But the experts think that the cathedral has a serious design problem.
20:08Outside, the vaults are too high and cannot withstand the pressure of the ceiling.
20:13So the sides have collapsed, breaking the vaults.
20:17But is the damage worth the increase?
20:20The crack is about 5 centimeters.
20:24If we compare it with the measures we took 4 years before,
20:28there is no increase in thickness.
20:32Which is good news.
20:35But the damage is not worth it.
20:38There is no increase in thickness.
20:41Which is good news for the cathedral.
20:49In Germany, in the cathedral of Cologne, the ceiling seems perfect.
20:54But is it?
20:59Doc Pritchard ventures under the roof to investigate.
21:03He wants to scan the vaults from above with a laser.
21:06Now we are between the vault and the oldest part of the building, the choir.
21:12What you will do is place the scanner here, in this open area.
21:18And I will combine the data collected with those of the scanning I did from below.
21:25So we will have a perfect cross-section of the cathedral.
21:29Doc expects his scans to expose the internal functions of the cathedral,
21:34and show it as never before.
21:38I think it's a fantastic image.
21:41It will clearly explain the architecture of the cathedral.
21:46The finished 3D image will show the cathedral with millimetric precision.
21:52From here, I will focus on this area.
21:56The most interesting thing about this vault is that it is a very thin membrane.
22:02And it is the pointed arches that support the weight of the entire structure.
22:08The columns transmit all that weight to the foundations.
22:12There are also the flying planks that press slightly inward.
22:16And all those elements, in harmony, allow the support of the cathedral.
22:21Doc's scanners pose an even more intriguing mystery.
22:26How did the ancient engineers build a vault 40 meters above their heads without collapsing?
22:36Researchers believe that the builders placed wooden scaffolding to the tip of the arches.
22:42Then they stacked blocks of stone on top of each other.
22:46To build the vault with such extreme precision,
22:50that the central piece fitted perfectly.
22:57Then they filled the gaps between the arches with light bricks.
23:02And they covered them with mortar.
23:05Finally, they removed the wooden scaffolding, praying for the ceiling to hold.
23:15The builders of the Colonia Cathedral created a perfectly balanced skyscraper.
23:21Hundreds of years before those of the modern era.
23:25And they built the vault with the help of their own hands.
23:29The builders of the Colonia Cathedral created a perfectly balanced skyscraper.
23:33Hundreds of years before those of the modern era.
23:37But how did this impressive cathedral survive centuries of wind, rain and natural disasters?
23:45The Colonia Cathedral is a remarkable survivor.
23:50This stone giant is located in one of the regions with the highest seismic risk in Europe.
23:56More than 120 tremors have struck the city.
24:01And more than 1,000 people have died.
24:05And more than 1,000 people have died.
24:09And more than 1,000 people have died.
24:12More than 120 tremors have struck the surrounding area for the last three hundred years.
24:16More than 120 tremors have struck the surrounding area for the last three hundred years.
24:20Causing the collapse of many modern buildings.
24:24So what is the secret?
24:27How did this mysterious structure survive the danger zone?
24:38Klaus G. Hinsen is a seismologist at the University of Cologne.
24:48He leads a group of specialists to the roof of the cathedral.
24:54They have come to collect data that reveals how the cathedral reacts during an earthquake.
25:00We started to monitor the cathedral in 2006.
25:04From time to time we have to do maintenance and to see how the space is working.
25:11Can you control left?
25:14These instruments are sensors that capture even the slightest movement in the church structure.
25:23On the left of the small screen we see the ground motion that is just being recorded here at the moment.
25:31It is clear that it works.
25:33I just have to hit it and look how sensitive it is.
25:38We are a couple of meters away from the sensor, but it still picks up the signal.
25:42The team helps Klaus predict what would happen in a major earthquake.
25:47We have had several strong earthquakes between 6.5 and 7 in the last 20, 30 thousand years in the area.
25:56Geologically this is a very short time span.
26:00And such an earthquake could happen at any time.
26:03It could happen today or next week.
26:06Fear that a major earthquake could break these cruising vaults.
26:13But Klaus's work reveals a very different behavior from the towers.
26:20Here we see a recording of a real earthquake.
26:23It was about 90 kilometers away from the cathedral at a magnitude of 4.5.
26:29The red traces are those that were recorded in the basement of the cathedral,
26:33which basically is the entry signal to the building.
26:36And we compare them with the blues that we see here.
26:39This is the motion of the tower.
26:42We see the tower starts swinging from one side to the other.
26:47And this movement lasts several minutes.
26:51It is an amazing mystery.
26:54How did the architects of Colonia create towers that swing like pendulums instead of collapsing?
27:06Despite the fact that its columns are not very thick, the weight of this building is not exactly light.
27:17The medieval engineers were in charge of creating the necessary support for all this weight
27:22with secret structures hidden underground.
27:26They accumulated 120,000 tons of rocks in immense foundations that extend underground.
27:35Practically the same amount as there is on it, balancing the cathedral perfectly.
27:48The founders of Colonia protected their cathedral with deep foundations.
27:53But in the Middle Ages, most people saw earthquakes as a punishment from God
27:58and thought that only prayers could prevent them.
28:02So did the builders really understand the action of the forces of nature?
28:13Archaeologist Rude Stinekbeck investigates her knowledge of the same terrain in which they built.
28:22Her search leads her to an archaeological excavation under the ground of the cathedral.
28:28Here, the researchers were amazed to discover that this pillar of the foundations reaches 16 meters deep.
28:36It is as deep as the pillars that support the Empire State Building in New York.
28:42But what really struck them was what they found below.
28:46Oh yes, that's the whistle.
28:49Water.
28:50And here we are with 10 meters and 47 centimeters from this point to the level of the underground water.
28:59The foundations are less than a meter above the freezing level.
29:05So why did the medieval excavators risk flooding their own construction site?
29:11Rude believes it was because they discovered an even greater danger.
29:15The city of Cologne and also the cathedral are standing on a layer of sand and gravel.
29:21The same we see down here.
29:23Look, it's nothing solid, just sand.
29:31The builders were concerned that the cathedral would sink into the sand of Cologne.
29:37So they decided to dig and build a wall.
29:41To minimize any risk.
29:45It must have been like digging in the sand of the beach, but how did they do it?
29:51If they had tried to dig a hole wide enough and deep enough at once,
29:56the loose sand would have fallen crushing them.
30:01So they dug in the sand of Cologne.
30:04The loose sand would have fallen crushing them.
30:09So they dug shallow steps,
30:12pointing the sides with wooden boards until they reached the level of the water.
30:20Then they interspersed layers of volcanic rocks and mortar
30:24to form huge pillars more than five floors high.
30:29This is how they built the solid foundations that have supported
30:33the 120,000 tons of stone in the cathedral to this day.
30:43Archaeologists have unearthed the remains of this ancient place of construction.
30:49Over here we have the base of one of the pillars that spans the cathedral
30:54and what we see is a mortar surface.
31:00Ruth believes that these slabs are the remains of the wooden boards
31:04that the builders used to contain the sand.
31:09You see one plank starts over here,
31:12and the next plank starts over there,
31:15and the next plank from over here to here.
31:22You see the structure of the wooden itself on the old surface.
31:26Right here you see the earrings of the wood.
31:35When I look at the wood I try to imagine how the people must have felt
31:39when they emerged down here,
31:41digging these very deep and dark pits,
31:44and they had to be afraid that the pressure of the earth
31:48would bring down the pits,
31:50and only those planks could prevent such a catastrophe.
31:55And so I think when you stand down here,
31:58you can kind of see how the people must have felt at that time.
32:12Archaeologists like Ruth continue to investigate this intriguing underworld.
32:21But there is another surprise above the ground.
32:28Above the beautiful vaulted ceiling there is a strange structure.
32:32What could it be?
32:41The Cathedral of Cologne is the most ambitious medieval cathedral in the world.
32:47This very high structure hides many amazing secrets.
32:52There is much more than it seems at first glance.
33:00Under the cover of this giant stone,
33:03a structure that seems out of place is hidden.
33:08It is a gigantic frame of thin iron beams
33:11that support the roof of 600 tons.
33:18Up to the Eiffel Tower,
33:20this was the most advanced iron construction on the planet.
33:28But what does this wonder of the world do?
33:32But what does this wonder of metal do inside a medieval building?
33:41Synchronous drawings record that the construction works of the cathedral
33:45stopped in 1530,
33:48and did not resume until more than 300 years later.
33:53This leads to a mystery.
33:55How did the builders of the century know
33:58how to finish the building?
34:02The chief architect, Peter Fiesenich, discovers the answer.
34:06A discolored design of the 13th century for the two towers,
34:10which was thought to be lost,
34:12but which was accidentally rediscovered almost 600 years later.
34:17The architects of the Cathedral of Cologne in the 19th century
34:21were lucky enough to find this medieval design.
34:25And they were able to build the facade,
34:28fulfilling the dreams of the medieval architects.
34:33The sketch, called Plan F,
34:35looks like a modern plan,
34:37but it has no dimensions or instructions.
34:43This Plan F was not conceived as a construction plan,
34:47but was made to convince those who financed this cathedral, of course.
34:52So, did the builders of the 19th century do a good job?
35:00The stone restorer Sophie Hopner
35:02belongs to an army of experts who have discovered
35:05how the final builders had to make some concessions.
35:13Sophie and her colleagues are going to solve a problem
35:16of the overwhelming construction of the cathedral.
35:19The work of the stone restorer is comparable to that of a doctor.
35:26The medieval builders preferred to use a hard stone called Traquita.
35:32But the rock of these overwhelming buildings of the 19th century
35:35is soft sandstone, and it is already beginning to crumble.
35:44What we have here is a rock,
35:47and what we can see here is a deteriorated area.
35:52The rain falls on this side and erodes.
35:57This part is drier,
36:00and the dirt has accumulated on top.
36:05It darkens due to air pollution,
36:08and in these areas, the rock is like sand.
36:12It gets washed out, and that is much clearer than the rest of the stone.
36:32If you put this hand on the rock,
36:34you see the stone is like a sponge.
36:37During the rain, the water gets into the pores of the stone,
36:40and when the stone dries,
36:42every material that was in the water
36:45goes out and is staying on this surface.
37:01On this surface, there is a hydrophobic agent,
37:05so when I put a drop of water on it,
37:07you can see it stays.
37:11But some stones can be damaged to the core,
37:14without visible signs on the outside,
37:20so the team decides to probe the interior of the buildings
37:23with a special drill connected to a computer.
37:31Sophie's colleague Jasper drills the soft sandstone.
37:40The computer measures the drill resistance,
37:43which reveals weaknesses in the stone.
37:47The results are not positive.
37:52It was really, really bad.
37:54The first two or three millimetres were quite good,
37:57but the stone was quite hard.
37:59Afterwards, there was a collapse,
38:01so the rock made that piece.
38:03So there, the stone is really soft,
38:07and then it gets hard again after you see seven millimetres,
38:12it gets even better.
38:15The restoration team must repair and replace this rock.
38:18The stone doesn't last forever.
38:21We will use some reinforcing agent
38:24to make the stone hard again,
38:27and then we check whether it works.
38:32So why did the modern builders
38:34use this poor quality stone?
38:37The problem is that they didn't find enough material
38:40to finish such a difficult task.
38:46When they started to build,
38:48the only thing that existed was the back end of the church,
38:52the ruin of the south tower,
38:54and a huge hole in the middle.
38:58To get to that point,
39:00the medieval builders had to tear
39:02the upper part of a nearby mountain,
39:05but this source of stone was exhausted.
39:09So the builders of the 19th century
39:11had to get the thousands of tons of Nisca stone
39:14from many different sources throughout Germany.
39:21Then they used the highest scaffold of their time
39:24to place the stones and finish the cathedral
39:27in just 38 years.
39:31So did the builders sacrifice the quality
39:34in their career to finish the cathedral?
39:39Legend has it that something is wrong with the towers.
39:44Architect Doc Pritchard uses his scanner
39:47to measure their actual height.
39:51There is a certain mystery
39:53regarding the height of the two towers.
39:55Are they exactly the same?
39:57Is one higher than the other?
39:59Let's find out with the scanner.
40:03Doc starts the ascent inside the north tower.
40:13We're up on the north tower,
40:15at 100 meters of height.
40:17And what I'm going to do is set up
40:19the tripod and scanner
40:21inside so that we can capture
40:23the entire interior of the tower.
40:26This is the first time that the towers
40:28are measured with such precision.
40:33What I'm able to do is do a 360-degree scan
40:36of the entire interior of the tower.
40:39And that will give me a subset of the level data.
40:42The scanner can generate
40:44over one million dimensional points in a second.
40:47So within 15 minutes,
40:49we'll have a vast amount of information.
40:52Doc turns on the scanner.
40:57The final stone was placed
40:59at the top of the south tower in 1880.
41:02Construction took 632 years and two months.
41:08Doc makes an amazing discovery.
41:13Looking at the data,
41:15comparing the height of the south tower
41:17and the north tower,
41:19they are almost exactly the same height.
41:22The south tower is just slightly,
41:24slightly taller than the north tower,
41:26only 4 centimeters,
41:28which is really impressive.
41:30Also, if you consider the age of the two towers,
41:33that really reveals a lot of the knowledge
41:36and the skill of the people
41:38who built this building.
41:42Doc's images are a precise digital copy
41:45of the cathedral.
41:48They reveal how generations of artisans
41:50were faithful to a design
41:52that is more than 700 years old.
41:57When you compare this building
41:59with contemporary buildings,
42:01what's really amazing here
42:03is that everything is done by hand,
42:05by craftsmen.
42:07Everything from individual stones
42:09to the entire structure.
42:11And that is really significant.
42:13It isn't made from another factory.
42:15Everything is done by hand.
42:17The vision behind it,
42:19by the people that want to see it,
42:21is incredible.
42:23It is a really significant building
42:25in its size and its beauty and its grandeur.
42:33The Cathedral of Cologne,
42:35like its predecessor in Amiens,
42:37is an extraordinary achievement.
42:41Today, millions of people
42:43pass through its doors,
42:45richly decorated,
42:47to contemplate the first skyscraper
42:49that took many lives to complete.
42:57The Cathedral of Cologne
42:59continues to inspire fear and devotion
43:01today,
43:03thanks to its huge Gothic arches
43:05that revolutionized architecture
43:09and a dazzling interior
43:11bathed in the sun
43:13through the thousands of
43:15glass fragments painted.
43:25The size and complexity
43:27of the Cathedral of Cologne
43:29continue to amaze engineers today.
43:37Its two emblematic towers
43:39stand out as lighthouses,
43:41attracting visitors
43:43from all over the world
43:45to this medieval wonder.