Inside Ancient Rome: How Its Greatest Monuments Were Built

Founded more than 28 centuries ago in central Italy, 30 kilometers from a maritime outlet on the site of seven hills, Rome is considered the second cradle of Western civilization, after Athens. The most populous city in Italy today has 4,300,000 inhabitants within its urban area. Rome is also the third most visited city in the world, with more than 10 million foreign visitors every year. On the one hand, because it's the only city in the world to contain within it a state, the Vatican City State, subject to the authority of the Pope, that attracts Christians of all nations. But also because of the city's own archaeological heritage, grandiose. Here, there are so many ancient monuments, all of them both artistic and technical achievements. How, one wonders, did the Romans accomplish such feats? They achieved the impossible with this unique monument, the most complete and best preserved of all antiquity, the Pantheon. Its architecture is extraordinary. No such thing had ever been seen before in antiquity. A gigantic environment, in which space and light dominated, with this circular shape, completely original, which was then copied in so many Renaissance buildings. Located on the Piazza della Rotonda, in the historic heart of Rome, the Pantheon reflects a desire to welcome all the religions of the Empire, gathering all their gods in one great temple. It is topped by a dome 43 meters in diameter and weighing 4,535 tons, the largest in the entire Roman Empire. It is destined to be a model of architectural perfection. The Pantheon has been standing for more than 2,000 years. It all starts with a novel plan. The temple, in two parts, reconciles two types of construction, two different forms, one rectangular and the other circular. This has never been seen before. What's striking about the Pantheon is that it's an architectural feat, created to provoke surprise. So we look up and we see a temple, but we barely see the dome behind it, almost not at all. We're already struck by the monumentality of the columns, which are monolithic columns made of a single block. 11 meters for each barrel, that's 42 tons or so. Each column is the height of a four-story building and weighs as much as an A320 Airbus. So they had to think about how to transport these huge long pieces. They needed ships that could transport them from Egypt to Ostia. We know from Egyptian hieroglyphics and other ancient texts that the Romans could build ships capable of carrying loads of over 100 tons. And from Ostia, the blocks headed upriver to the port of Rome. Once mounted on a wooden sled, the column was towed along. It must have taken 10 teams of 20 oxen to haul the column to the foot of the Pantheon. When we look at things like these columns, and we're amazed by the strength of them, by the fact that the building stands here all these years, it's natural to think, how did the Romans calculate this? How did they do that? And, you know, we think of modern engineering. Now, first of all, Roman architects and engineers weren't separate people. They were one and the same people. And the next thing we have to bear in mind is they were very practical, empirical, and they had a lot of experience. They had decades of experience. But that is not the big surprise. Inside, one crosses through a building of white marble. And the second space is revealed. And one is under this huge dome, which is actually a complete sphere, since the height of the lower half is equal to the radius of the dome above, 43 meters. Never has a dome of this size been built in the history of the world, in the history of mankind, until the invention of reinforced concrete. It's the largest dome in the world. And there are no pillars. This is an entirely new type of construction. Incredibly, they managed to build it without any support. You have to stand right in the center of it to see how the Roman builders had the idea to use the volume of a sphere and thus to create a whole new form. Just how did the Romans develop such a skill? By using a revolutionary new material, concrete. Concrete definitely represents a revolution in Roman constructions. First of all, in terms of its composition, Roman concrete is a mixture of lime, sand, water, of course aggregates. Basically, it's modern concrete. Now, this amazing material, Roman concrete, it has the great advantage that it can be made by semi-skilled people. What's more, the Romans discovered that when they added to this lime mixture some pozzolana, which is a type of volcanic stone, or some tile, that is, fragments of crushed tiles or bricks, there was a chemical reaction between the lime and the pozzolana, or the tile. It caused the stone to become stronger and more waterproof, the more that water was added to it. This Roman mortar completely transforms construction. Now their ideas can be realized on a large scale, quickly and well. The Romans built using two sidings of brick cladding filled with small stones or pebbles. This technique, similar to casting, will be as important to ancient builders as concrete is to those of today. Mortar would free the Romans from the Greek heritage of the straight line. And this meant they could go on to perfect the arch and the vault that will both characterize Roman architecture and become widely used in all grand constructions. The design of the Pantheon is especially innovative, particularly because of its circular form, and not only for its shape, its plan, but also, and above all, for its roof, this extraordinary dome which holds up all on its own. It symbolizes the celestial vault, home of the gods. It weighs 4,535 tons, the equivalent of 16 Airbus A380s. But how did these Romans build such spectacularly high vaults? The dome of the Pantheon must have been built in several stages. First of all, they built a framework of wood whose layout corresponded to the future segments or caissons. The second stage consisted of a thin layer of vaulting composed of ribs made of bricks and mortar. The third step was to manufacture and install a negative framework inside each caisson. Then they merely had to fill in the concrete in bulk, thus revealing the result without all its framework. The dome has 140 caissons. The cells have been deliberately offset to increase the effect of... The fourth step was to reinforce the dome with a skeleton of brick arches. The higher it rises, the lighter is the mortar, incorporating more pozzolana, the abundant volcanic stone that's as light as pumice. The dome will be covered with concrete. It's a construction principle that allows the load borne by the outer part of the vault to overhang it and transmit the pressure back to the lateral pillars. Then they covered the building with a skin of marble or stucco veneer inside and tiles on the outside. I wouldn't say you could call much of their architecture beautiful or refined. Words like pretty, no. I mean, they're solid, chunky, business-like, sensible. The daylight is used with theatrical skill by the central opening at the summit, an oculus or eye nearly nine meters in diameter. The light follows the course of the sun, giving the impression that the dome rotates to the rhythm of time, seeking perhaps to restore the divine mystery. And that's what makes the Pantheon unique. You enter the Pantheon and you see this gigantic space with this light coming from above. The building techniques that the Romans used were in large part learned from the Greeks, which is of how you take small pieces, not these large bits of marble. So you have bits of brick, fist-shaped-sized bits of stone of various kinds, and you mix it together in a medium that is the, if you like, the glue. And so the Pantheon is about the absolute maximum they ever got to. They never did a vault any bigger than that. I mean, I think you have to realise that the building has got quite severe cracks. I mean, it's something of a miracle it hasn't fallen down. And they were probably alarmed by these things, but it held. And they didn't go any bigger than that. You can get an idea of its longevity simply by remembering that these walls are six metres thick. Of course, in their manufacture, the walls were then to be adorned and decorated with plaster. The bricks were covered either in plaster or, in the more luxurious houses, in marble veneers. Unfortunately, all these marble veneers have disappeared, and what we are left with are the skeletons of monuments. This dome will remain the largest in the world for over a thousand years. Just two kilometres to the southeast of the Pantheon, another masterpiece for the people is still defying the centuries, the Colosseum. The Colosseum is the emblem of an eternal Rome and a unique testimony to the techniques and the modernity of the Roman builders. At more than 50 metres, it is impressively high, and to build it took 100,000 cubic metres of white stones. The biggest amphitheatre of them all, designed in the first century A.D. under Emperor Vespasian, still stands in the heart of the city. It remains the most visited monument in Italy, with six million tourists a year, an oval amphitheatre that remained in use for 500 years. And it could hold more than 50,000 people. That's equal to our biggest modern football stadiums. Built for the entertainment of the people, the Colosseum was a place of spectacle for the Romans. These days we can only visit 35% of it. Its front columns are a real catalogue of the three Greek styles, Doric, Ionic, and Corinthian. The Colosseum took eight years to build, with another two years for the finishing touches. So how did the Romans manage to build a monument like this in such a short time? The Colosseum was built so quickly for two reasons. First, thanks to using concrete as a construction material. For example, the Colosseum's foundation is extraordinary. A huge concrete ring. And then there was the large and low-paid workforce. Price was a factor in all that. And the result is gigantic constructions built in relatively short time. From the latest archaeological excavations, we know that the Romans had envisaged a system of pipes under the Colosseum that both brought in and evacuated a large quantity of water, several thousand cubic meters. This water would later be used for the spectacles. Once the pipes had all been laid, the foundations were set in place. They are gigantic foundations that are like a kind of ring on which the structure then sits. It's incredible, a huge concrete ring about six meters thick. On either side of the ring, we have found two brick walls 12 meters high by three meters wide, into which they poured concrete, cubic meter after cubic meter of concrete. Then, on an axis radiating from the center of the arena, the stone pillars were erected. Like the Greeks, the Romans used hoisting machines for their big constructions. The Treatise on Architecture by the famous Roman architect, Vitruvius, provides records of the loads lifted by these machines. Most texts had all got lost. And the only treatise on architecture, the only serious work we have, is just one by this architect, Vitruvius. And so all this knowledge has been condensed down and come through this, and it's the single text. He may not even have been the greatest writer or the greatest architect, but it's what we have. How do you lift a one-ton load? We know that a fit man is capable of lifting an average of 67 kilos. So just by pulling, it would take 15 men to lift that ton, because the force exerted is equal to the weight of the load. If you add a pulley, the mass is halved. It takes only seven men. If you then add a second pulley, the weight is divided by four. So we can infer that it takes four men to lift a load of one ton. But then the hemp ropes had to be able to take the load. Vitruvius indicates that a rope four centimeters in diameter could support a load of two tons. At ground level, there were 76 numbered passages for ordinary spectators to enter by. The remaining four were reserved for the elite. On the upper level are 80 vaulted arches, all molded and identical. More than 50,000 spectators attended the shows. Engraved tokens were used as tickets. That means that when people arrived at the Colosseum, they had a token with a number on it for a particular entrance, not just anyone. They showed the number of the arcade, the staircase, the row of bleachers, and the seat. The Romans once or twice had experience with riots and things in amphitheaters. So they were very aware of the need to be able to get people out of the building quickly. With its bleachers, its corridors, its stairs, and numerous entrances, the Colosseum was every bit as functional as our current stadiums, even in their security. First of all, because it's built on a hollow structure. So you have a whole sort of circulation system that is big and wide and efficient, and so it means that if there's trouble, you can get people out quickly and efficiently. Five minutes was all it took to get all the audience out if there was an incident. The Colosseum is 188 meters long by 156 meters wide and more than 50 meters high. No other Roman amphitheater equals it in size. Here, the Romans built the largest backstage of Rome. A complex of incredible galleries, hundreds of people in the shadows, elevators, gladiators, beasts, all took part in these amazing shows. And the people were all wild about these shows. Nothing at the time was so popular, with all the hunts and the fighting gladiators, of course. In the morning, it was men fighting against wild animals. They were up against lions, against tigers, against elephants, even against sea creatures. At midday, they took advantage of the animals being there to carry out some executions. The condemned were devoured by the animals, and this time, they couldn't fight back. They were tied up and unarmed. And then in the afternoon, it was gladiator fights, which would, of course, end up in injury or death, but which always took place with a referee and in pairs, one gladiator versus another. The arena where this spectacle took place formed a giant stage 86 meters long by 54 meters wide and 4.5 meters high. The underground part of the Colosseum was divided by a main axis. We can still see from the network of galleries how the basement of the Colosseum is like a Swiss cheese, made up of passages and rooms for storing maintenance equipment. It was the backstage of the shows. The arena was covered with a layer of sand about 20 centimeters thick. It featured, in places, moving wooden plates designed to release from below a multitude of stage effects. It thrilled the crowd to see wild animals or gladiators appear as if out of nowhere. This wonder was made possible thanks to a few concealed lifts. In the underground part of the Colosseum, known as the Hippogia, were a warren of passages and 28 elevators for the animals. Each wooden cage measured 1 meter 80 by 1 meter 40 and was 1 meter high. It weighed 500 kilos and could support loads of up to 300 kilos. It took 8 men to hoist it to a height of 7 meters. The beasts would make their surprise appearance up a slope and into the arena. They might be lions or panthers or sometimes bears. Just imagine what a grand spectacle these games at the Colosseum were conceived as. Some of the spectacles depicted episodes from mythology in which somebody died. And the person who died was, unfortunately, someone who had been sentenced to death. Ingenious stage machinery meant the scenery seemed to emerge out of nowhere. These platforms would also hoist up fake mountains, rocks and trees to suddenly create a whole scene in the arena out of nowhere. It was really a great show. They say that the Emperor Titus, famous for ordering 100 days of games in a row, sacrificed 5,000 wild animals on the day of the Colosseum's inauguration. To the east of the Colosseum stood the largest gladiator school in Rome. It was directly connected to the Colosseum by an underground tunnel. This prestigious school is called Ludus Magnus. Today, only a part of the arena that was used to train gladiators still stands, as well as a few rooms. It could accommodate 3,000 spectators. Around the arena, there are still 14 rooms to be seen. Presumably, they served as accommodation. The gladiators were either slaves or enlisted freemen. It was a rectangular building made of bricks 100 meters long by 180 wide. There is no doubt that to be present at the gladiators' training session was a privilege. They were as idolized as the football stars of today. To heighten an aura of mystery, the gladiators from the school secretly entered the backstage of the Colosseum through this tunnel. Ludus Magnus is just one example of the incredible number of infrastructures set up to ensure that the great shows of the Colosseum would work their magic. Archaeologists have unearthed three other gladiator schools. Also close to the Colosseum was a morgue, an armory, and the storage buildings for sets or stage machines for the battles. The games went on all day, from sunrise to sunset. However, summer in Rome is stiflingly hot, and the white stone of the Colosseum reflected an awful lot of heat. In Mediterranean regions, you can't sit in bleachers all day in full sun, especially in July or August. This made the whole place suffocating. They had to quickly come up with a solution. The Romans came up with the solution of an impressively huge awning. The total surface area of this vellum, as it was called, was 22,000 square meters, and it weighed 12 tons. It was operated by hundreds of men. Thanks to researchers, we can now present a reconstruction of this vellum. How did the Romans manage to stretch a sunshade 50 meters high to cover a 500-meter oval? Well, first of all, there was a central ring of ropes which was hoisted up with a system of ropes leading up to the top of the bleachers. Attached to pulleys, they were raised on a number of masts that encircled the whole arena. These small holes matched to ones lower down, 2 meters from the summit. There are 240 of them. They served as a solid support for the 240 masts that passed through the holes and were erected all around the amphitheater. These masts were about 20 meters high, and they supported retractable awnings that left only a central ring uncovered. When there was a show-on, all over this great spider's web were spread linen canvases. On the Colosseum, this was a big operation because it had to cover 22,000 meters squared. So, what with the weight of the canvases, the weight of the ropes, the pulleys and all that, that makes 12 tons. It's a huge thing. And maneuvered by at least one person per sector, i.e. 240 canvas sectors, that makes at least 240 people. Then, there were the officers who gave the orders, as well as the musicians who transmitted the orders, probably with trumpets or horns. And there were most likely at least 300 people up on top of the Colosseum to unfurl the vellum. The ropes were connected to winches outside, attached to mooring bollards. Five of them are still there today. And the holes in them tell us just how the winches were attached to them. So, there was a special team of sailors stationed at a barracks nearby. Sailors from the town of Miseno, where Rome's fleet was harbored. And these sailors were responsible for maneuvering the vellum, which had to be opened and closed as needed. It's a whole military operation to make everything unfold and be lifted into place at the same time. So, these sailors were very experienced men. They had to lower those canvases in three or four minutes flat. That's really very fast. The canvases were colored, mainly in red. And the colors from them would play over the people in the crowd. Nothing was too beautiful when it came to showing off the power and wealth of Rome. The Colosseum, though, has an unexpected secret. Its location. It was built on the remains of the huge palace of Nero. Nero wanted a place to live that was truly exceptional. One that only an emperor could aspire to. The Golden House, or, in Latin, Domus Aurea. An illustrious palace of more than 200 rooms that formed a huge architectural and landscape complex of 80 hectares in the heart of the city of Rome, taking over a quarter of the city. The building of the Domus Aurea was an extraordinary project. Extraordinary from a financial point of view. Some authors agree that Nero spent insane sums of money there. It was here, east of the center of Rome, on the Opian Hill that Nero founded his sumptuous home. The Domus Aurea would stretch over several hills from the Palatine to the Esquiline. Almost completely gone now, the palace lives on in myth. Its construction posed new problems and was a huge challenge to its builders. It is a set of buildings, but also of gardens and of technical feats. These days we call it a high-tech house. Nero wanted to amaze and impress. He wanted to see real feats of technology. The sacred way is widened and ascends to reach the vestibule, where stands a colossal statue of the emperor depicted as Apollo. At 35 meters high, the statue of Nero dominates Rome. If the columned porticos are popular, they have been tripled here and on three sides for a total length of one kilometer. Everything here is supersized. The main façade faces south in order to bathe in sunlight all day long. Next, a visitor was treated to the site of this rectangular artificial lake surrounded by service rooms, baths and monumental fountains that demanded huge amounts of water. Of course, a palace like the Domus Aurea needed a lot of water. Even the Stagnum, the lake that Nero built and that was later the site of the Colosseum, consumed vast amounts of it. At the time, at the end of the imperial era, there were 11 aqueducts that brought water to Rome, about one million cubic meters of it each day. Ancient Rome's one million inhabitants consumed about 1,000 liters of water per capita, which is a lot more than what we consume today. Currently, our average water consumption amounts to 150 liters of water per day per capita, almost seven times less than the Romans of the 4th century AD. But you have to understand that water was used for a lot of things. Public toilets, for example, were constantly rinsed by flowing water. It was also used in public baths, which were huge consumers of water. Fountains were also fed continuously, without taps. So there was a perpetual flow of water. This is also one reason for Rome's high consumption of water. It was essential that the water consumption of this palace be regulated. The Romans had already exhausted all the springs and rivers in the area. They had to search further away from Rome now to find water. And it was 60 kilometers away that they found a source, and the construction of an aqueduct could begin. The water crossed the countryside underground, before rising to the surface through a hidden pipe high up in the grand arches of the aqueduct. The aqueduct crossed the city to end up not far from Nero's palace. Here we discover the Opius Pavilion, the best known of them all, with 240 square meters of remains. Built of bricks and Roman concrete with vaults, it reveals huge rooms more than 10 meters high, all of them for ceremonies and receptions. In this palace, luxury and innovation went hand in hand with marvels of engineering. Thus was born, amidst the vineyards, a bold project, the mythical revolving dining room of Nero, a fine example of Roman genius. The ruins we see today are just the remains of this basement, which resembles that of a tower. There was a tower with a colonnade at the top, and inside, a dining room that was constantly revolving. That is something extraordinary. Suetonius, a Roman historian of the first century, describes it like this. The main dining room was round, and it turned day and night on itself, imitating the movement of the world. But how did this revolving dining room work? It was a French archaeologist, Françoise Ville-Dieu, who unearthed it in 2007. And we now understand how this revolving dining room was made, a 12-meter-high tower at the top of which is installed a turntable of about 12 meters in diameter. This means that it rotates continuously and slowly. A 3-D representation of the building might show how it worked. Let's consider the three problems faced by the builders. First, there was the choice of a suitable architecture. Secondly, they had to invent a mechanism to ensure that the turntable rotated smoothly. And thirdly, they had to find a way of driving it that would guarantee perpetual movement. So first, they decided on the tower. It consisted of a circular central pillar in solid masonry, four meters in diameter, connected by eight arches to a circular wall over two meters thick that surrounded the entire building. A door in the central pillar gives access to a spiral staircase that connected the ground floor to the first floor. This was the first time that such a staircase was ever seen, a 75-centimeter-wide spiral service staircase. Secondly, they had to ensure that the plateau overhanging the tower moved smoothly. Right at the top, and at the exact center of the structure, a hole 13 centimeters in diameter and 30 centimeters deep suggests there was a central pivot. Other regularly placed cavities were probably there to hold bronze spheres. These spheres sat on a bed of fine clay and were equipped with two fins that attached them to the wooden plateau, so they functioned like ball bearings. Then, what must have been a complex rotating moving floor adorned with precious wood had to be placed on them. Thirdly, they still had to come up with a driving force that would keep the whole thing turning steadily. The moving floor would be driven by a mechanism powered by a hydraulic wheel. A special branch of the AquaClaudia aqueduct would channel the water to this great wheel that would transmit the force of that water to the mobile floor through transmission axes equipped with gears. The dining room revolved very slowly and probably took two hours to turn a complete circle so diners could enjoy the changing view without getting dizzy. All these amazing amenities are what the Domus Aurea was all about. Not only an astonishing building in terms of its surface area, but also extraordinary in terms of its technical equipment. The incredible palace would be destroyed a few years after Nero's death. Its imperial monuments may well be sumptuous, but Roman architecture is characterized by its utility and its functionality, and defending the city was one of its primary purposes. Rome has preserved the remains of two walls, the oldest, the Servian Wall, and the largest wall in the west, the Aurelian Wall. The Servian Wall, built in the 6th century B.C., was the first accomplishment. The fortified enclosure certainly followed an older wooden and clay palisade. You can see a large part of the ramparts as you leave the Termini bus station and admire the walls. They were made with large blocks of yellow tuff from the Tiber region. Tuff is a type of volcanic rock since Rome is situated close to two volcanoes. It is made of opus quadratum, which means it consists of blocks placed on top of each other, dry and without using mortar, then joined by metal staples. The wall is 3.7 meters wide and 7 meters tall at its highest. It had 16 gates in it. But in the 3rd century A.D., the city expanded considerably, and Rome had to protect itself from barbarian invasions, which is why it built the greatest wall in the West. It was Emperor Aurelian who decided to build it. It would become the largest construction site in Rome that century. The walls were built in just five years. The impressive construction stretches for 19 kilometers and surrounds an area of nearly 14 square kilometers. It is built according to the molding technique. Two brick sidings form the exterior of the wall. In the center, Roman concrete has been poured. 3.5 meters thick and 8 to 10 meters high, it is punctuated every 30 meters by towers that defend the city. By about 500 A.D., the wall had 383 towers, more than 7,000 crenellations, and 18 main gates. The Aurelian Wall is remarkably well preserved, mainly because it was in constant use right into the 19th century. Rome in its imperial period may have been splendidly opulent, but it wasn't like that at its beginnings back in the 8th century B.C. The legend tells how it was founded in 753 B.C. by Romulus on the very place where he and his brother Remus were found by a she-wolf. The history of ancient Rome can be divided into three periods. A monarchy to start with, then a republic, and finally an empire. Clearly, the greater part of the ruins in Rome are from the imperial period, the richest period of the city's history. Power is concentrated in the hands of one man who is ever freer to do just what he wants and, over time, to undertake major projects with no accountability. The second reason is that during the imperial era, Rome became the complete master of the Mediterranean world and took for itself all the intellectual and material riches of the Mediterranean rim. Alexandria and its museum became a second home for Roman engineers. The Romans could now easily head off to find marble in Africa, in Egypt, in present-day Turkey, or in Greece. All the riches were now at their disposal. And the extraordinary thing is that these little hills, at first nothing more than small hills in Lazio, a region of swamps on the banks of the Tiber, became the capital of the Mediterranean world. It became the model for all the cities built around the Mediterranean. And that's why we can say that Rome is, at the very least, the cradle of western urban civilization. The power of Rome had grown into an empire of over 3 million square kilos and its authority will extend over 90 million inhabitants. Rome is the most populated city of the ancient world. It's thought that in the first century A.D., there were about 1 million inhabitants of Rome. That's a colossal number. It really is a megapolis. Think about the fact that Rome is six times smaller than Paris, Intramuros, in surface area. Paris, Intramuros, it's a little more than 2 million inhabitants. Rome, 1 million inhabitants. On a surface area, six times smaller. The population lives crammed into narrow, winding alleys. With everyone lacking space, Rome becomes gripped by a housing crisis. Well, that meant that to house all those people, you had to build upwards. People lived in this block of buildings. Using bricks made it easy to construct multi-story buildings, and that's how the insulae came about. The insulae, or islands, are multi-story buildings usually intended for housing. They are not luxury housing, just ordinary dwellings for ordinary people. And it was a pretty unique city from the point of view of antiquity. One that impressed everyone. When you got to Rome, you'd see buildings that could be six, seven floors high. The wealthiest tenants lived at the bottom of the buildings. It was the opposite of today, for reasons that are easy to understand. Firstly, there were no elevators, and secondly, and importantly, there was no water distribution to the upper floors. The tenants had to bring jugs and vases to stock up from the tub at the bottom of the stairs, probably filled at one of the city's 1,352 fountains. Thirdly, a lot of wood was used in these buildings, and fires were frequent. Now fire is a very big problem in a traditional building when there's timber. Vaulting, you know, the brick and all that, that helps, obviously, but you're still going to have some timber up on the roof and the floor. So the higher up you lived, the more dangerous it was. For heating and cooking, they had portable braziers and oil lamps for lighting. And obviously, with all these braziers and oil lamps hung around the place, or being carried about, or standing on the furniture, if one gets knocked over, it's a catastrophe. In the Imperial Age, there were more than 46,000 insulae. At the height of its Imperial Age, Rome covers 2,000 hectares, 20 kilometers squared. It is the biggest megapolis in the Western world, a sacred capital, and a model for all the peoples of the Roman Empire at its highest point. The figures can make your head spin. In 314 A.D., there are in Rome 11 forums, 200 temples, 11 large bathhouses, 12 basilicas, 2 amphitheaters, and 43 triumphal arches. But also 37 gates, 19 aqueducts, 5 circuses, 2 nomachia, the artificial lakes where naval battles are recreated, 967 public baths, 1,352 fountains, 3 theaters, 9 bridges, 11 commemorative columns, a stadium and an Odeon, 46,000 buildings, hundreds of warehouses and thousands of shops. The most exceptional of the ancient Mediterranean cities and the largest of them all, Rome will forever remain the emblem of the power of the Roman Empire and an example of architectural excellence. The quality of Roman concrete, the new forms that freed up space, the numerous innovations combined with the perfect technical mastery and talent of its artists, they leave us a unique universal heritage. With this dome that brings together all the gods still standing firm. Along with the moving lost beauty of the Domus Aurea, that fabulous palace born of Nero's megalomania, where one can dream of the Colosseum's engineering treasures, Roman architecture never ceases to amaze us. By placing technology at the service of the Roman way of life, it knew how to combine functionality with not just greatness but also luxury and beauty for eternity.