Château de Chambord: The Renaissance Masterpiece Linked to Leonardo da Vinci

Château de Chambord, the jewel of the French Renaissance. Situated 110 miles south of Paris, lost in the middle of a forest, is one of the most impressive château in the Loire Valley. Its outline is enthralling. Its extravagance is overwhelming. With 156 m facade, this château has more than 400 rooms, 77 staircases, and 282 chimneys. Chambord isn't a château, it's a masterpiece. Surrounded by a 5,500 hectare park, the equivalent of a small city, this château's design is still a thing of wonder five centuries later.

How were they able to achieve something so perfect in the 16th century? We're going to talk you through this incredible project, which required monumental resources in the 16th century. 1,800 workmen worked on this project over the years. It was an exceptional project. What technical feats did these builders accomplish at the time in order to put together these revolutionary structures? This piece cannot be dismantled without the whole thing breaking. That's what's exceptional about it. We are dealing with something completely unique. From the monumental central staircase to the thousands of sculptures to the hundreds

of chimneys that sit atop the building, what challenges had to be overcome in order to satisfy the every whim of the château's commissioner, King Francis I? The king takes a decision and it gets done. Taking on this project really became something of a financial drain. A project that also holds the story of a mystery that's never been solved. We have absolutely no floor plans at all. Why does the shadow of Leonardo da Vinci, the greatest genius of the Renaissance, loom across the Château de Chambord? He called Leonardo da Vinci my father.

He was in awe of this illustrious old man. Using new 3D animation software, we'll roll back the clock and explore the timeline of this incredible structure, unique in its time. I don't think we could create something better even now. Accounts from the best specialists will reveal the construction secrets behind this stone giant, now kept under very tight surveillance. 500 years after its construction, the secrets behind the Château de Chambord are finally being revealed. The Château de Chambord looks like no other royal building in the world. That's what has made it such a popular attraction.

Each year, almost 1 million visitors come to roam through the corridors of this distinctive château. As you walk in, you feel like you're getting lost in a maze. On each floor, you have to go to the windows and look outside and think, "Okay, I'm on this side now." Otherwise, you'll lose your bearings. It's a château that's very hard to fully conjure up in your mind. It houses 440 rooms, some of which have 6-m high ceilings. It has 77 staircases, more than the Palace of Versailles, and its corridors are as long as an airliner. This château is a giant architectural treasure hunt.

The sheer size and organization of Chambord posed a challenge. Chambord is a cryptic message. With its non-standard dimensions, it was able to conceal some of the Louvre's greatest works of art during the Second World War, including the famous Mona Lisa. It was like Alibaba's caves with boxes wherever you looked. 3 to 4,000 crates were stored in Chambord. At one point, Chambord had 4,000 cubic meters of works of art, statues, and crates. However, this château, featured on the UNESCO World Heritage List, very nearly never came into existence. While it was being built, nobody believed such a project was possible. No one, except one man.

The year is 1518, here in the Loire Valley city of Blois, the home of the new king of France. Francis I is only 24 years old, and he's already the most powerful king in Europe. Francis I in 1515 was a feisty young man. He was an ambitious king, a strategic king, and a visionary, too. We know his aim was to somehow become the emperor of Europe. In 1515, King Francis I had conquered the Swiss in Marignano. So, this young man, who wasn't necessarily supposed to ascend the throne, suddenly had everything. To demonstrate his power, King Francis I wanted to build things and mark his own era. Very quickly, he launched a huge construction program.

He was a construction king. He's one of the greatest historic builders. And when he walked into his château, he'd draw sketches of what he'd done and what he wanted to do. And I imagine he'd have been an architect had he not been king. Over the course of his reign, he built 12 château, more than any other king. But King Francis I wanted to go even further. And in 1518, he decided to invent a new type of château. One of his goals was to have a hunting château where the king could go with his ladies and his friends. It was the king's youth project. He wanted to erect a charming and splendid building here. It wasn't simply about building a place to live, it was about

creating a unique architectural work of art. In order to build the château of his dreams, the king stopped at nothing. At vast expense, he hired the greatest genius of the Renaissance movement, Leonardo da Vinci. He invited him to France and offered him board and lodging. He had great admiration for this famous old man. He called Leonardo da Vinci my father. For Leonardo da Vinci, this project would be seen as his last chance to prove his architectural talents. At the time, he was 66 years old, and all his attempts had thus far resulted in failure. There were no architectural pieces by Leonardo. Leonardo had always, throughout his life, proposed extraordinary projects that were probably impossible to achieve because

they were too ambitious for what was actually technically possible at the time. Coming to France was a way for Leonardo da Vinci to make his dream come true, to finally behold a real construction project, a building that would no longer be on paper or parchment, but actually exist in reality. Everything was in place to create an exceptional château. And so began the pre-project meetings. King Francis I asked his team to think about the château's architecture. It was out of the question to use an existing building as inspiration.

He wanted this royal building to take on a revolutionary form. So, what did the first sketches look like? We have absolutely nothing. We have absolutely no floor plans at all. Most of the documents regarding the construction of Chambord were destroyed in the 18th century. It's a little disconcerting. It's as if someone wanted to make the plans disappear and perhaps maintain a sense of mystery around the construction and design of Chambord.

It wouldn't be until five centuries later that the mystery of the missing plan unraveled, a confusing yet ambitious floor plan of an extraordinary construction project. Here is the first floor plan of Chambord. What we now know is that this must have been a square building flanked by four towers with the living quarters in the corners. That was all that was to this initial project. It was a keep, but an extraordinary one at that. A huge keep measuring 2,000 square meters and 56 meters high. But the most surprising thing about it was the organization of the spaces in a central plan, a château in the form of a Greek cross, which was unprecedented at the time.

Dividing the internal space into the form of a Greek cross had never been done before. It was the first time in France that a civil building or château had used this layout. In the 16th century, royal château were all designed based on the same model, like the one used here for the Château de Blois. Normally in château, you walk into a courtyard, you see a staircase, which you climb to the first floor, and there you'll see a large room followed by the king's living quarters. Quite unlike this square structure cut into four by a cross where all the living quarters are identical, including those of the king.

The king had no suite of his own. The king was, in a very strange way, on a level playing field with other people. The keeps as a place with no hierarchy. Where a remarkable space. So whose idea was this architecture so totally innovative at the time? Was this Leonardo da Vinci's signature? Leonardo da Vinci was obsessed with centralized and super symmetrical layouts and he used them very often. It's probably what he'd consider to be the perfect shape for a building. The leading theory today is that King Francis I incorporated the great master's recommendations. But the Italian genius is believed to have hidden a coded message behind this design.

Initially, the building had a central symmetry. In other words, everything was organized around a central pivot. They set out a building project that adhered to an unrivaled symmetry, something that was completely unique. And they had what's known as a windmill layout. The same piece can be turned a quarter turn four times. And so the whole chateau is taken like that in a great movement of rotation and ascension. So there's really something there that reflects the spirit of the engineering behind it. This idea of rotation is an architectural hallmark of Leonardo da Vinci's. Leonardo had always been fascinated by swirls, anything that turns, anything that spins. And he'd find examples in nature, like whirlpools and whirlwinds.

What motivated and fascinated Leonardo da Vinci was perpetual motion. There are indeed sketches that reflect this movement in the Codex Atlanticus. Since he was, if you like, a master of all the sciences, to some extent, he combined them all when it came to his architecture. This extraordinary plan was approved by the king who was seduced by the Italian master's innovative ideas. But one, and by no means the least, technical challenge remained.

Leonardo da Vinci may have designed it, but they would still need to bring it to life. How could you get the workmen to actually make this? This became an even greater challenge since Leonardo da Vinci died on the 2nd of May, 1519, at the age of 67. Four months before construction began. His death did not stop the project going forward because King Francis had already decided that the chateau would be built come what may.

He put Leonardo da Vinci's architectural plan into motion. And so the builders had no idea of the scale of the task that awaited them on this extraordinary construction project. On the 6th of September, 1519, several hundred laborers arrived at the location the king had chosen for his chateau, which was an awkward choice to say the least. The name of the place was Chambord. A wild stretch of lowland isolated from everything. In the Middle Ages, palaces were normally built on hills, but here he'd chosen an area of lowland and in some notebooks, Leonardo da Vinci writes, "Use lowlands for buildings because it creates a greater element of surprise because you'll discover the building at the bend of a path."

King Francis I knew this land well and he must have roamed across it while hunting deer. So he bought the land to build the Chambord estate. King Francis I saw things on a grand scale, a very grand scale. The Chambord estate is the same size as a small city. 5,500 hectares with a 20-mile long wall, which makes Chambord the biggest enclosed estate in Europe. It made for wonderful hunting territory. But this location posed the builders problems. Because it's a very marshy area. And some of the wetlands are still visible today.

Personally, I wouldn't build a house on that kind of terrain. No, that would be technically impossible nowadays. Even at the planning stage, they'd say, "Woah, no, no, don't go there." Evidence of this susceptibility to flooding arrived in 2016 following record rainfall, leaving Chambord surrounded by water. The idea of building in the middle of a marsh and even extending into the marsh itself was a way of demonstrating that it was possible to surmount the landscape and overcome natural elements.

Chambord dipping its toes in the water was actually King Francis I's initial dream. It's 2.5 miles from the Loire River and Francis I's intention, which we know because of archives of orders he made and invoices for his orders, was to divert the Loire River, which wasn't far away, and turn Chambord into an island. An abandoned project that came to life 500 years later thanks to flooding. But the chateau only narrowly escaped the water in 2016 thanks to the exceptional quality of its foundations, which had been built five centuries earlier. Simon Bryant is an English engineer who specializes in excavation operations in the Loire Valley chateau.

According to him, the greatest challenge faced by the laborers was making sure the building didn't collapse. You have to find a base so the buildings with several stories and chief stonework just don't collapse because small movements in the foundation, even little compressions, can sometimes have rather devastating consequences. In the late 1990s, Simon Bryant launched a huge excavation operation at Chambord. His aim was to understand how a chateau comprised of 220,000 tons of stone, or the weight of three aircraft carriers, was able to remain upright on unstable terrain. So he started digging beneath the chateau when all of a sudden the scoop of his

excavator became blocked. The scoop of an excavator hit on a hard surface. Oh well, look at that. There are walls here. So we had to remove the water, clean up, and that's when we realized that this was the base of a medieval tower. He had found a medieval tower that had not previously been known about. In this photo, we can see part of its base. So there was a smaller chateau in Chambord that predated the one built by King Francis I and the builders used it to support their new construction. They saw that the medieval stonework was solid enough in that location and could be incorporated into the new construction like a foothold.

They tore down one chateau, left a few remnants of it. And on top of that, they built a new one. But that wasn't enough because the size of the chateau King Francis I had envisaged was much greater than that of the former fortress. And so a huge landscaping project began. 5,000 m³ or the equivalent of two Olympic swimming pools were dug up in the hope of finding soil hard enough to build the foundations with. They realized they'd gone beneath the limestone. So in places they dug as deep as 5.2 m or even deeper. 5.2 m of stone foundation is quite extraordinary. And so on top, they built these wooden partitions like braided bits of mulch, which they poured lime into. And lime mixed with water holds firm. So

the more lime you add, the more it hardens. And then on top of that, they gradually added stones, all the cut stone, thus forming the base of the chateau. It wasn't until four years after the project started that the foundations were actually finished. Four years of digging and compacting the soil before they could even start building the walls. A monumental task. In addition, the original teams assigned to manage all of this were all quite old, died shortly afterwards, and had to be replaced. So there were some fairly complex setbacks for the project to begin with.

But the difficulties had only just begun for the Chambord laborers because it was now time for them to build the most architecturally important part of the chateau, the keep's central staircase. Whichever way you enter the building, it's the first thing you see. It's really magical. It's really a key structure. It's really a work of art within a work of art. It was the first time someone had given so much importance to a staircase within a building. A splendid staircase with a rare technical characteristic.

It's a double helix. In other words, it's made up of two 176-step spirals, which set one atop the other without ever merging. It's a bit like the structure of DNA. For this construction project, sculptors and stonemasons would be working on a double helix staircase of inordinate proportions. It's almost 9 m in diameter and over 20 m high. It was the first time someone had made this kind of thing. As incredible as it may seem, the tools the builders used for the staircase were as basic as hammers, calipers, and ropes.

So, how were they able to produce this architectural feat that still remains unparalleled to this day? The first clue lies 12 mi from Chambord in King Francis I's first chateau. One of the main models for making this was a basic staircase, the staircase in the Chateau de Blois. This giant single ascent staircase is very aesthetically similar to that of Chambord with its exposed banisters. This is evidence of the inestimable expertise of the region's craftspeople, whom King Francis I was relying on for the construction of his masterpiece. And it was certainly no coincidence that the master stonemason from Blois was then sent to Chambord

because it required a great technical mastery, particularly the way they grouted the stones and joined it all together, which was no mean feat. It was a lengthy endeavor. Each stone had to be cut according to the drawings and the sketches. In reality, all the blocks were positioned perfectly and adjusted without joints. It was completely transparent. And so, this means the workmanship is just phenomenal. In order to truly appreciate the remarkable quality of this creation, the Chambord staircase was scanned by a group of researchers in 2011.

The staircase is, by its very nature, extremely three-dimensional. So, a conceptual plan cannot do this staircase justice. The only way to represent it in a relevant way that can be significant enough for use in the future is to see it in 3D. Over 200 scans were required to reproduce the Chambord staircase in 3D. And the result was astounding. So, you get a sense of the whole space and you can see through the material. The digitalization then makes it possible to create a unique model of the staircase.

It's the first and only model of its kind. To my knowledge, it's the first time there's been a 3D print of this level of quality from a laser scan of a staircase this big. This model is proof of this staircase's perfection. The demonstration is really all about the movement and realizing that you can unscrew it. If it wasn't perfect, you wouldn't be able to unscrew it. So, this movement isn't possible unless the geometry is perfect. I don't think we could create something better even now. It's as simple as that. Even with our modern technology, I don't think we'd be capable of doing any better. But, one question remains regarding this architectural feat. Who was the designer?

Leonardo worked a lot on simple staircases, double staircases, triple staircases. He was the multi-staircase specialist. This theme kept rolling through his head and among the group who designed this extraordinary chateau, it absolutely had to have been Leonardo whose idea it was to give it several twists and also to place it in the middle of a building with a central plan. 5 years after the work began, King Francis I's dream started to take shape. But, a terrible event threatened the whole project. In 1524, King Francis I went to wage war in Italy and was captured during the Battle of Pavia.

It was the equivalent of a world war at the time. King Francis I was imprisoned in Spain, thus placing the continuation of the work on Chambord in danger. So, there was no money for Chambord and construction stopped. For 2 years, the project was placed on hold. In October 1526, the king was finally liberated in exchange for his two sons. He decided to resume construction of the chateau. But, there was one small problem. He wanted to review the initial design and demanded modifications, which would ultimately have serious consequences. When King Francis I returned to France in 1526, Chambord started changing shape. In October 1526, they decided to expand Chambord and to add to the existing keep, which had been built up to the first floor.

And to add a whole system of walls with two wings, the royal wing on one side and the chapel wing on the other. It would involve building an extra several thousand square meters, a colossal task for the laborers. I believe his state of mind had changed and Chambord now needed to be updated to reflect the life of a king who may have been young, but was becoming increasingly king-like. There was no way the king could be housed in the same keep as his court. He wanted his royal accommodation sheltered from view.

What he really wanted was to distinguish himself from the masses of courtiers who visited Chambord and no longer live in the keep. Moving into a wing would reaffirm his distinction with bigger living quarters that were different from the others. I love this royal abode because on the first floor, you have King Francis I's bedroom, his living quarters, and his chapel. And then you go up a small hidden staircase to find the bedroom of the king's mistress. I love it because it's spiritual pleasure and then carnal pleasure. How wonderful. This royal wing proved to be a real brain teaser for the builders because they had to completely rethink the architecture of the keep. In order to enable circulation between

the keep and the royal wing, they had to flip one of the corners. Otherwise, you couldn't get through. You would hit a wall. So, they decided to flip the corner in order to integrate a passage into one side, a loggia that linked to the royal wing. A reversal that made the project even more complicated. Not only was he breaking from the original plan for the keep, which had perfect geometry, but he was also forcing them to modify some of the stonework that had already been built. This is the case for the chateau's latrines, the septic tanks of that time. They were formed of a double cesspit, a big one and a small one connected by a pipe from the higher floors. But, it was impossible to preserve this system in the north tower once it had been inverted.

In the north tower, since it had been necessary to invert the tower, the pipe could no longer reach the small cesspit nor the big one. So, the men building Chambord had to change the structure of the cesspits in the north tower as discovered by archaeologist Jean-Sylvain Caillou and researcher Dominique Hofbauer. There's still water there. Yes, it's rather I'm not even sure we can get in there. Since the flooding in 2016, the cellars are often flooded. Dominique Hofbauer dons a waterproof suit to show us the modifications made to the latrines by the Chambord stonemasons. So, here we're in the latrines of the keep's north tower, which is a system of

latrines comprised of a small cesspit, but this one is much longer than those of the other towers. And then there's a bigger cesspit, which is much narrower behind this wall. And what we've discovered through archaeological digs is that these two cesspits of different sizes are actually one big standard cesspit. Based on the same model as the others, and they've been divided into two separate cesspits. And our geophysical surveys have enabled us to establish that the small cesspit was, in fact, built using the plan that respected the building's central symmetry. But, through lack of usage, it was backfilled and subsumed into the foundations.

This discovery has therefore irrefutably proved that this famous north tower was indeed inverted in order to form a link with the royal wing. And that's not the only modification the king demanded of his teams when the building work resumed. He added an external staircase, which totally obstructed some of the existing windows. The gallery was built. The fifth window was ready and perhaps the joiners were kept waiting and were about to fit them when, unexpectedly, the king decided to have a stone staircase built behind it. So, they completely walled up this window instead. The king takes a decision to get it done.

It's like a permanent adjustment. It's a balancing act with the builders adapting to the monarch's every whim in some ways. As the years went by, this architectural dream turned into a nightmare. Delays were multiplying, costs were going through the roof. If we look at the years 1531, 1533, and 1534, the most active years, expenses were as high as 60,000 tour pounds. That's more than all the chateau and ongoing building projects in and around the capital at that time. To put it into perspective, a cathedral project back then would have cost around 5 or 6,000 tour pounds per year. This one was 60,000 tour pounds per quarter.

The equivalent of hundreds of millions of euros. Staggering amounts. Taking on this project really became something of a financial drain. And the costs grew heavier due to the horrendous conditions. Working on this royal building project was hellish for the builders. The surrounding swamp area brought with it its fair share of troubles, such as marsh fevers, which people caught from mosquitoes. In other words, malaria killed a large number of workers. Others, it is said, were suffering from extreme fatigue. And we know that King Francis I was happy to reward his workers with additional bonuses so they'd be more inclined to work tirelessly on the project, often in danger of risking their life.

The greatest difficulty for the workers on this project was transporting raw materials. Chambord was in the middle of nowhere. Incoming materials had to pass through an obstacle course. The slate came from Angers. Lead came from England, and wooden blocks of stone came from Tours. To travel distances of hundreds of miles, the workers had but one solution. It was very difficult because at the time heavy goods were normally transported by river. They were flat-bottomed barges that traveled along the river and were generally pulled by horses.

These barges could carry cargo weighing several tons, but were very sensitive to bad weather. It was slow. They had to follow the path of the Loire. Fortunately, winds came from the west, which helped push the sails of these boats. But when the wind stopped, they couldn't move forward and transportation became complicated. It's important to remember that the weather conditions were a lot more dramatic than they are today. There are diaries telling us that the rivers froze over for a month or two, thus rendering transportation by water impossible. The journey was far from over because the boats were not able to dock directly up to Chambord.

Their port of entry was located 2.5 miles from the building site on the banks of the Loire River. The journey was completed by horse and carriage, and cargo breakages cost them time. At the time, the roads were not paved, and the carts would cross dirt paths with smaller loads. So it took hundreds and hundreds of carts to transport these stones to the project. The Chambord project was an unprecedented logistical challenge. It wasn't just a small project with a few dozen workers. It was now a huge building site. 1,800 men worked on the project. It was the first time this many builders had worked on a single project.

The king's in a hurry. He wants the beautiful Chateau de Chambord to be built as quickly as possible. There was a huge amount of pressure on the workers. There's no doubt that labor laws were violated. King Francis I imposed a fine on the boatman of the Loire for failing to deliver the 20,000 stone blocks he'd ordered, for not delivering them on time. And the reason the king was so intransigent with this boatman was that the delivery involved the most important raw material required for the construction of Chambord, Tuffeau stone.

It's a very aesthetically pleasing stone because it's almost pure white. Over the course of the project, more than 220,000 tons were extracted from a 75-mile underground quarry in Touraine. It's a stone with an incredible advantage. It's very easy to sculpt. It's a stone that actually contains as much emptiness as it does matter. Half of its volume is air. I don't even need a hammer for this stone because it's really very tender. So you can carve it straight away, like a sculpture. In other words, you can actually use a tool to remove it without really hitting it hard. Because it's very delicate, it can be used for lots of things, especially intricate decorations.

A characteristic the king particularly liked. This Tuffeau stone made it possible to reproduce what he'd seen in Italy. These sculptures were possible. All the finesse of the Renaissance sculptures were possible thanks to this stone, which is very soft. Thanks to this Tuffeau stone, there are 2,500 sculpted decorative pieces at Chambord. These absolutely extraordinary Renaissance-inspired decorative elements are extremely rare. Of the thousands of sculpted works of art, one required a considerable effort. It can be found at the top of the double helix staircase. What's particularly impressive is the great hall on the top floor of Chambord, which is vaulted with very powerful, very Italian-style coffered vaults. And the coffers are sculpted into King Francis I

emblems. In each coffer, you'll find either a salamander or an F. In total, there are almost 400 coffers. There are around 200 F's and around 200 salamanders. To create such an excessive vault, the builders had to erect a wooden scaffold. A sort of casing. Once installed, the sculptors placed the coffers on top of one another, starting from the bottom. Once the last stone, called a keystone, had been placed in the middle of the vaulted ceiling, the workers could remove the casing. Thanks to the perfection of this construction, these compressed stones would hold themselves in place without any support. You cannot remove any of the coffers in this vaulted ceiling. Everything is slotted into place. This creation cannot

be dismantled without the whole thing collapsing. That's what's extraordinary about it. This piece was built, it's here, and it's here to last as long as necessary. But one strange coffer attracts our attention. Could this coffer contain a hidden message? There's an F on the vaulted ceiling that's strange because it's been sculpted backwards. Of all the coffers in the space, there's only one that's backwards. So was this a joke on the part of the sculpture, or is it a symbolic way of saying that the F we have above us is turned toward God rather than men? It's also maybe a way of saying that things can be read in both directions.

An inverted letter. The same approach used by Leonardo da Vinci to record his research in his notebooks, the famous codex. Leonardo da Vinci actually had a rather spectacular writing style. Much like 15% of left-handed people, he had a unique ability to write in mirror. Was this King Francis I's way of paying tribute to the Italian genius? It still remains a mystery to this day. Perhaps this backwards F is one of the symbols beyond our comprehension, and we should either reinterpret or at least observe it.

In 1540, 20 years after the building project started, King Francis I's dream, despite its ups and downs, was gradually taking shape. But the sovereign fell ill. Having developed an infection, his suffering grew worse. Would the king have enough time to see his masterpiece completed? A race against the clock began to finish the roof. 20-meter-long frames had to be erected. And the slate needed to be placed on the roof. The workers had to work together to build the roof terrace of the keep. All these big stone structures emerging from the rooftops are what we call superstructures.

Huge chimneys, webs of staircases, skylights. Really, this whole structure looks like a city perched on top of a keep-style chateau. In the center of the 282 chimneys lies the jewel of the chateau, the lantern tower, sitting at 56 meters high and decorated with a crown and a giant 1.5-meter fleur-de-lis. Up there, at the top, is the finest royal crown. In other words, the crown reserved for the imperial leader. That is to say, the crown that represented the greatest power in the world at the time. This exquisite tower weighs more than 40 tons, or the equivalent of a military tank. This weight, in addition to the other superstructures, required the construction of special walls that could support this excess weight.

Some of the walls are almost 2 and 1/2 m thick. You should see the walls at Chambord. They're absolutely huge. But the greatest challenge of this lantern tower was its elevation. How can you get 40 tons of stone 56 m in the air with brute force alone? They know the weight. They know the risk of crushing or something similar. And any wooden scaffolds may just collapse. Yet again, the laborers had to adapt their techniques to the excessiveness of the tower. They used a simple but extremely effective tool, the famous treadwheel crane.

It had large wheels in which a man or several men would pedal like hamsters, if you will, and could lift rocks and large stones to high altitudes using a pulley system. Thanks to this ingenious system, one man can lift an object much heavier than himself. This was also a building site that helped advance techniques. Based on studies that have been done, one wheel could lift as much as 4 tons, which is huge. And the genius behind the builders of Chambord didn't stop there. Recently, during the renovation works carried out five centuries after its creation, Chambord has revealed a previously incredibly well-hidden secret. Beneath the slabs of the roof

terrace hides a water drainage system designed to protect the building from bad weather. Further proof of the talent of the architects of that era. The slabs aren't watertight. The water gets through, and the problem is that the coffered vaults are just below them. As a solution to this, they developed a hydraulic drainage system, the likes of which had been seen in France. The idea is that beneath the rooftop slabs, the stone slabs, there's a real roof with tiles like this in a U-shape, which collects the penetrating water from the rooftop and drains them into two conduits at the base of the vault,

which are slightly tilted outwards. And then they link with the small lead channels towards the water spouts. The construction of this chateau almost saw completion, but everything stopped in March 1547, 28 years after the project had begun. King Francis I died of septicemia at the age of 52. The king never lived to see his architectural masterpiece completed. We've obviously tried to look into how much time King Francis I spent at Chambord. Based on what we now know, it was around 73 days.

The Chambord project lasted 28 years under King Francis I, but the building wasn't complete because the chapel wing hadn't been finished by the time King Francis I died. The enclosure around the courtyard had been started but not completed. His son, Henry II, took over the project for a few years. But it was Louis XIV, the Sun King, who added the final touch to this masterpiece. This was around 1680, more than a century and a half after the project had begun. Louis XIV finished it, respecting the overall design. He didn't add any Baroque wings. He did change the style of some of the windows, but he was aware that he was in the presence of an incredible work of art. In order to finish the work, Louis XIV

brought in the best in the business. He came with the mastermind behind the Hall of Mirrors at Versailles, Jules Hardouin Mansart. At Chambord, Jules Hardouin Mansart finished the work on the chapel. He built the attic spaces atop the lower enclosure. But the Sun King didn't stop there. He created a whole new backdrop for this unique chateau. Louis XIV felt as though it wasn't just the chapel and lower enclosure that were left unfinished. The area immediately surrounding the chateau was still a swamp. I think they quite often found themselves traipsing in water. And that didn't suit the Sun King. He decided to reproduce here what he'd successfully implemented at the Palace of Versailles, a splendid French garden. As revealed by the garden restoration

work carried out in 2016, it would have been a tireless struggle against the weather conditions in Chambord. They needed to divert the Cosson, the waterway that meanders around the chateau. This garden was a monumental construction project. They made the decision to channel the Cosson and divert it well away. In order to do so, they created artificial moats and an artificial 6-hectare raised platform. Then they needed 15,000 little border plants and over 800 trees. So this garden was just further extravagance. By creating this splendid garden, now restored, Louis XIV was honoring the spirit of his famous predecessor, turning Chambord into a chateau for social occasions.

He invited Molière there to put on his famous play Le Bourgeois Gentilhomme. But nowadays, 500 years later, Chambord is a giant mass of stone with clay feet. The famous tuffeau stone is being eaten away at by a mysterious disease. Here's a bit that's healthy. Which sounds full. When you knock here. It sounds hollow. So this is where the crack has started spreading. Tuffeau is a soft stone. It's a porous stone, and it absorbs water. And then it dissolves and eventually falls. And if chunks of stone fall, that can be extremely dangerous both to the public

and to the building itself. A few years ago, a huge block of stone fell on the terraces and fortunately did no harm. But this does show how urgently Chambord's stone disease must be diagnosed. Since 2011, the chateau has been granted an in-depth medical examination carried out by a team of scientific experts. Myself at Chambord, I'm like a stone doctor. In other words, at Chambord, I take samples, like a blood sample you'd give at a hospital. I then analyze the sample and identify the disease. Is it healthy? Are there pollutants involved? Is there something wrong with it? If there's something wrong with it, where's the problem?

Using X-ray analysis of the samples and temperature sensors, more than 14,000 stones at the chateau are being referenced and monitored on a permanent basis. Chambord is the only chateau in France with its own health record. This health record lets us know whether the stone degradation is speeding up in certain places or whether we can actually wait a few years while we work on an area that requires more urgent attention. Faced with this danger and this disease eating away at the stone, action had to be taken. For several years now, teams have been busy renovating this Chambord treasure. And it's a sizable challenge.

Even just replacing a few stones, erecting a scaffold, redoing a few sculptures can cost 2 million euros in one go. This masterpiece is now under strict surveillance and is still yet to reveal some of its secrets. In recent years, researchers may have uncovered new avenues to unravel the mysteries behind the initial Chambord design. An initial design that might not look the way we'd expect it to. Until now, we believed that the enclosure part wasn't foreseen in the 1519 design, but as it turns out, we're having doubts about that now. Perhaps it was foreseen. But it would have been completely separate from the keep, which would have

been very distinct and separate from the enclosure. It's a 2.7 m. In order to check this, further excavations have been carried out in the chateau's moats in the hunt for remnants from the past. And there are older pieces of stonework that could perhaps correspond to an extension of the lower enclosure. We're measuring them, and then we'll compare them with some of the designs to try and see whether we're on the right track. If this line of research proves true, this could mean that the keep was never meant to stand alone, but be surrounded by a huge square enclosure. An architectural design that's reminiscent of certain religious texts.

The design with the courtyard and surrounding walls was used for the ideal city. Heavenly Jerusalem in the Apocalypse according to St. John. Was King Francis I much-desired Chateau de Chambord designed as a representation of God's home on Earth? What's interesting about this hypothesis is the very mathematical interpretation of this new design of Chambord. In other words, they have had this 3x3 grid with nine squares with the keep occupying the central square. It was an extremely intellectual and mathematical design.

You can't help but recognize the marks of one of the greatest geniuses of all time, Leonardo da Vinci. He was convinced that the world was written in a mathematical language. Ultimately, Chambord's a bit like a stone version of Leonardo da Vinci's Mona Lisa. Almost two centuries of work, technical feats, and engineering genius helped this mesmerizing and majestic chateau rise from the ground. A gargantuan project for a legendary chateau. If King Francis I's aim was to dazzle the world, then he certainly succeeded.