[dramatic theme music plays] They appeared out of thin air and within a few generations, they became masters of a great empire. [narrator] In the center of the Aztec Empire: a floating fairytale city in the middle of a lake. At that time, one of the largest cities in the world. [man's voice] A city which eclipsed anything the Spanish had ever seen in size and glory. [narrator] The Aztec rulers are skillful statesmen. Everything in their empire is perfectly regulated. Their empire is much more modern than European societies of the time. The school system of the Aztecs was particularly impressive, because it was compulsory for both boys and girls. [narrator] But this advanced civilization also has a dark side: cruel rituals in honor of the gods. For a hundred years, the Aztecs rule over Central Mexico. But at the peak of their power, they make a crucial mistake. [battle cries] [narrator] Their fall is unstoppable. [male voice] It was the year 1519. We called it the Year of the Reed. A messenger brought news of strangers who had come to our country. I can still picture them to this very day. They were carried by strange animals and had terrible weapons. They were so pale. Some of us believed they were messengers of the gods. Our enemies had become their allies. But we did not yet know what misfortune their arrival signified. [narrator] With eleven ships, 500 Spanish conquistadors land on the coast of the Aztec Empire in April 1519. Their leader: Hernán Cortés. They are attracted by the legendary wealth of the Aztec capital, Tenochtitlan. The news of the arrival of the Spanish spreads fast. Relay runners carry the message over paved roads into the capital. They can cover 500 kilometers a day. That makes them faster than the mounted messengers of Europe of that era. [male voice] Our wise leader, Moctezuma, received daily reports of the approaching aliens. I was a young scribe at the time and had the honor of taking notes of their news. You can't say the Aztecs were unsuspecting. We know that the Aztec ruler had his spies. He knew they were there as soon as the Spanish set foot on the Gulf Coast. He had very precise descriptions of them. [narrator] Moctezuma wants to avoid unnecessary bloodshed. So at first, he warmly receives these mysterious strangers. He had such a great empire. He had such large military units, which were immediately ready for action. But in my opinion, he didn't see the Spaniards as a threat. Which was a mistake. [narrator] His guilelessness suits the conquistador Hernán Cortés and his men very well. In November 1519, the Spanish reach the mountain villages above Tenochtitlan. So far, nobody has stood in their way. The legendary riches of the Aztec capital now seem within reach. The sight of this huge metropolis exceeds all their expectations. The sources tell us that when the Spaniards descended from the mountains, they saw the whitewashed buildings reflected in front of them, and they could not even grasp the size of this city in a lake. None of them had ever seen anything like it, and some of the people accompanying Cortés had traveled far, had seen Rome and other cities in Europe. But this eclipsed anything they had ever seen before. [narrator] Tenochtitlan looks like a floating city to the Spanish, in the middle of this large lake. Over 250,000 people live here. At the center of the city: the holy district with temples, pyramids and the ruler's palace. Where once the city of the Aztecs was, the metropolis of Mexico City rises 500 years later. The lake is long since drained. Today, 21 million people live in the densely populated basin. For a long time, it seemed as if the Spanish had erased all traces of the "floating" city of Tenochtitlan after the conquest. But there is still much of Tenochtitlan to be found beneath the modern Mexico City. The current center of Mexico City was once the sacred district of the Aztecs. The Spaniards simply built over it. The ruins of Templo Mayor, the most important sanctuary of the Aztecs. In 1978, the temple pyramid is rediscovered during construction work. Since then, researchers have been searching the entire city for traces of the built-over past. Raúl Barrera coordinates the excavations. Mexico City possesses immense archaeological wealth. And the Templo Mayor is probably the most important archaeological site in the city. [narrator] This temple pyramid resembles the success story of the Aztecs. With the expansion of their power, their central sanctuary also grew. They are still clearly visible today: the foundation walls of the various stages of expansion. Again and again, older versions of the pyramid were simply built over. Archaeologists can now accurately reconstruct the dimensions and appearance of this impressive structure. The pyramid was about 60 meters high. On the top platform there were two shrines dedicated to the god of war and the god of rain. Like all other buildings in the city, this pyramid rested on piles that were laboriously driven into the muddy subsoil of the lake. Remains of this construction can still be seen today. Archaeologists are on site at every major construction project to make sure no valuable relics are lost forever. We must protect these traces, preserve them. For they are our past. They give us our identity. That's why the finds we make here in Mexico City are so important for us. [narrator] Each find tells a story, gives the scientists a deeper insight into a world as the Spanish experienced it 500 years ago. Hernán Cortés meets the Aztec ruler for the first time on November 18th, 1519. Moctezuma presents the Spaniard with a valuable necklace and precious fabrics. Cortés thanks with beads of cheap green glass. For Moctezuma, an exotic gift. The Aztecs weren't familiar with glass. Moctezuma invites the Spanish into his palace. [man's voice 2] There's a lot of stories that he was treated like a godlike figure, that nobody can look directly at him. Those are stories that were created during the colonial period and later in creating this image of an oriental despot. Which was not the case. [narrator] Cortés himself later reports about the legendary wealth of the Aztec prince to justify his actions. The reality must have been somewhat different. [Fargher] These sorts of stories probably emerged to glorify him in a sense and make him to be something that he wasn't. And actually, the amount of portable wealth in gold and so on really disappointed the Spaniards. [narrator] So far the archeologists haven't found much gold during their excavations. [Fargher] There was a find a few years ago, but apart from that, you could only fill a little table with gold. It's not like the Inca. The Inca were famous for their amount of gold. [narrator] But at the beginning, the Spaniards still hope for great riches. Cunningly, Cortés tells Moctezuma about the "Spanish disease." Only gold could cure it. But the ruler and his advisors probably quickly recognize the danger that threatens their empire. They wanted to convince him that they're really... "Okay, so yeah, I live pretty nice, but I don't have a lot of stuff and so on. So you guys don't really want to conquer us. You know, we can be friends. You know if you want us to make some sort of alliance with your ruler, we're willing to do that and so on, and then go home." That was, sort of, let's manage this on a political level. [speaks indistinct Spanish] [narrator] The Spanish should see with their own eyes that an alliance with the Aztec Empire would be worth more than chasing after treasures of gold. [male voice] Our wise Tlatoani allowed the Spaniards to explore our city. I was allowed to accompany them. [narrator] The tour through the city does not miss its effect. Cortés will later give an impressive description to his king. When the Spanish reach the central market, they are overwhelmed by the sight. So many people in one place... They had never seen anything like it. 20,000 to 40,000 people flock to this market every day. Farmers from the surrounding area come here to offer their goods for sale under the shade of the arcades, as do long-distance merchants from the entire Aztec Empire. Whether everyday goods, food, animals, luxury articles or even slaves and military equipment, at this market, you can simply buy everything. [male voice] The Spanish saw many new things. They especially admired our fine fabrics, which we dyed red with the juice of pressed lice. It was quite clear that this marketplace eclipsed anything they had ever seen. And the goods, most of which were foreign to them, fascinated them even more. Especially if they contained gold, which was of course what these conquerors wanted most. But they were also fascinated by the smaller things: the order that prevailed at the market, the fact that market supervisors carefully made sure that everything was in its proper place. All of this made a huge impression on the Spanish. [narrator] State inspectors inspect the goods offered here, and traders must register. There is a separate area for each type of goods on offer. If the goods are particularly valuable, payment is made with grains of gold. Cocoa beans are a popular currency for all other products. A hare costs about 100 beans, a tomato only one. It often happened that the cocoa beans as a means of payment were forged. There were people that attempted to fake the cacao beans. They'd take wood... Cut wood out, polish it and shape it so it looked like a cacao bean. And so that was one of the major reasons that they wanted people to trade in the markets. Not only could they tax them in the markets, but they could provide market security. [narrator] Thieves and fraudsters are handed over to the market judges on the spot. On pain of death, the accused must swear to tell the truth to the judges. The sentence is carried out on the spot. For the maintenance of public order is the first priority. Those who have stolen must pay off their debts through slave labor. In medieval Europe at the time, there was very little judicial structure. In contrast, the Aztecs were very concerned with that. They were very concerned with public order and protecting citizens. [narrator] Unlike in European cities, the Aztec state also pays attention to cleanliness. Cleaning staff sweep paths and public places daily. The cleanliness in the city itself couldn't be compared with the grubby cities in Europe in the 15th and 16th centuries, if I may say so. We know there was hardly any functioning sewage system. There was hardly any functioning drinking water supply. And Tenochtitlan had achieved all this. [narrator] To prevent the city's canals from becoming cesspools, the Aztecs even had an ingenious toilet system. They probably had public toilets for very urgent business. Excrement and urine are collected separately in clay jugs. A good deal for the city's fecal matter merchants. They sell the composted excrement as fertilizer for the fields. The urine is used for dyeing fabrics and for tanning leather. In some ways, the urban life of the Aztecs was reminiscent of what we would today call a "zero waste" society. For example, the collection of feces and recycling as fertilizer, recycling of waste in general. All this was done systematically here. [narrator] A world as if carved out artificially. A state created out of thin air. Because 200 years before the arrival of the Spanish, the Aztecs were still simple nomadic warriors. It all starts with a myth. [male voice] Our people were without a home. But our tribal god showed us the way. [narrator] According to legend, the Aztec people wandered aimlessly for many generations. Finally, on a small island in Lake Texcoco, their mythical leader Tenoch sees the divine sign promised to them by their tribal god: [intense atmospheric music plays] [male voice] An eagle on a cactus, devouring a snake. This is where we should settle down and build a temple to honor our god Huitzilopochtli. [narrator] And so their chief lays the foundation stone for the city of Tenochtitlan... the city of Tenoch. But what are the facts behind the legend? Today, we assume the Aztecs created this founding myth themselves. They could thus present themselves as colonizers of a new country, as the first arrivals. Although, as we know today, they were not the first, but in fact the last to arrive in the basin of Mexico. [narrator] Scientists suspect that the Aztecs immigrated around the year 1215 from northern Mexico or the southwestern parts of today's USA to the already densely populated Mexican highlands. There, the nomadic warriors encounter the descendants of the once powerful Toltecs and the pyramids of the mysterious megacity Teotihuacan. At the time of the Aztecs, it's already in ruins. Only giants or gods, so the newcomers believe, could have built these enormous buildings. According to their belief, this is where the world came into being. The American archaeologist David Carballo has been researching this unique place for many years. He and his colleagues have ascertained by now that the Aztecs took these ruins as a model for their own city. This is what they wanted it to look like. They wanted to imitate the gods. The Aztecs were very inspired by Teotihuacan, the first great city of Central Mexico. They saw it as a place of creation, as a place where the gods sacrificed themselves for humanity and to get time started. [narrator] The floor plans of the residential buildings and palaces that once dominated the cityscape are still clearly visible. They give the researchers an impression of what Tenochtitlan, the city of the Aztecs, must have looked like later on. But the Aztecs not only copy the architecture. [Carballo] They looked to Teotihuacan as the civilized precursor who had arts and calendar systems and writing systems that they drew on very consciously in creating their own empire. [narrator] In the beginning, the warrior nomads hire themselves out as paid mercenaries. They go to war for the local lords of small city states. But they are unwelcome. And the only place left for them to go, because they had angered just about everybody in the Southern Basin, was this little tiny island in the middle of the brackish swamp. There was only about two square kilometers an area, and that's where they were almost forced to settle. [narrator] At that time, the island is considered uninhabitable. What they need to survive, the Aztecs have to bring from the mainland in their canoes. On the island itself, there is neither timber for huts nor drinking water. The lake is very salty, and its water is brackish. It's a meager life that the first settlers are living. The future splendor of Tenochtitlan is still a long way off. Systematically, the inhabitants of the small island also engage in land reclamation behind an artificial dam that separates salt water from fresh water. On a subsoil of water lilies and reeds, they pile up ever new layers of mud in the shallow water of the lake, which later solidifies. In this way, the Aztecs created "floating" gardens to practice agriculture. The Chinampas. On the outskirts of Mexico City, they still exist today. Farmers still cultivate these "floating" gardens and grow the same plants as their Aztec ancestors did 500 years ago: corn, beans, pumpkins. But also tomatoes, avocados, chilies and sweet potatoes. These are plants that were first domesticated in Mesoamerica, and are now grown all over the world. The Chinampas create more space and make the Aztecs independent of food from the mainland. This will become the basis for their incredible ascent. So the Aztec system of Chinampa fields was a highly productive form of agriculture. It could allow between three to eight crops grown per year, depending on what the plant was. So the population boomed as a result of it. And so at the height of the Aztec empire, there was at least a million people living in the basin of Mexico. [narrator] In just 200 years, the small island settlement has developed into a flourishing metropolis covering 13 square kilometers, the center of the largest state power in Mesoamerica. [male voice] I am one of the last to make the past glory of our people known. All is destroyed, and most of those who could remember are dead. [narrator] Decades after the fall of their empire, Aztec scribes under the supervision of Spanish monks wrote reports about their lost culture. Today, these records are the only authentic written legacy of the Aztecs, in their own pictographic writing. We know the Aztecs had a lot of books. They had veritable libraries. Unfortunately, these were burned, destroyed. And even after the fall of Tenochtitlan, systematically eliminated to drive out "the belief in the devil," as the Christians put it. And the codes that have survived are all the more important for us historians, because they give us an insight into history, into the life of the Aztecs from their own point of view. [narrator] One of the few remaining manuscripts is the Codex Mendoza. For a long time, the pictographic writing of the Aztecs was barely deciphered. Text annotations by Spanish monks help scientists to understand the records. The Codex Mendoza contains a large book about the everyday life of the Aztecs. And this is particularly unique. [narrator] A life in which everything is regulated, from the cradle to the grave. The Aztecs consider the birth of a child as a life-threatening and bloody battle. [dramatic music plays] [narrator] The "battle of the mother" equates her to a warrior. To die in childbirth is as honorable as death on the battlefield. [groaning] [baby cries] [traditional ululations] [narrator] A shrill battle cry of the midwife is therefore the first thing an Aztec baby hears. [male voice] I was born in the year of the 10th rabbit. My mother was a slave. But I was free. [narrator] In the Aztec world, the children of slaves are born free. After birth, the umbilical cord of girls is buried under the fireplace of the house, that of boys is given to a warrior. He must later bury it on the battlefield, so that one day, the child will become a great fighter. The Aztecs also had godparents. They give presents to the newborns symbolizing what the future holds for them. For boys these are miniature weapons, as a reminder and warning that they were born to be warriors. On several pages, the code gives precise instructions for the education of children. Yes, we can see that the children were assigned specific tasks according to their age. The younger children had to help in the household, and the boys were mostly given smaller auxiliary tasks outside the house. Increasing with age. [narrator] Boys fetch firewood, go to the market, work in the fields or help with fishing. Girls learn to prepare corn dough, weave and sweep the house. If they do not obey, children are punished severely. Some of these punishments seem particularly harsh and torturous to us. For example, this scene of an Aztec teacher holding a boy over smoking chili peppers, clearly bringing tears to his eyes. [narrator] Boys who don't want to obey are beaten or even pricked with thorns. Intractable girls get their hands tied, and they are threatened with beatings. The Aztecs certainly loved their children. However, they had a different understanding of life and the world. They were firmly convinced that each person, according to his or her status and age, took his or her place in society and had to uphold the established rules. The state takes care of young people's education, maintaining schools, paying for teachers. For us today, the Aztec school system seems modern because it was obligatory for both boys and girls. A general school system. If we compare it to Europe at the time, they only had schools for the chosen few, but not for the general public, and it was not compulsory to go to school. [narrator] Between the ages of eight and ten, girls and boys are introduced to the gods and religious ceremonies and learn to dance and sing. [male voice] I was allowed to go to school and study. That's how I could become a writer. [narrator] Even for the children of slaves, compulsory schooling applies. Schooling for girls usually ends after five years. For boys, education continues. Aztec history, agriculture and military drill are on the curriculum for them. In the schools, general knowledge was imparted about the history of the Aztecs. It can also be said that a certain ideology was imparted here. Of course this strengthened the identity and the affiliation of the children to the Aztec society. More so than if they had been educated by their own families. [male voice] I, too, wanted to become a great warrior, but the gods had a different plan for me. I proved to be particularly adept at interpreting our characters. So my teachers decided that I should become a scribe. That was one way to work your way up: through education. If you're a brilliant individual, they didn't really care what social strata you came from. They wanted to get you into the administrative structures. [narrator] Especially gifted boys, even from the lower classes, have access to secondary schools, which are normally reserved for the nobility. They attend a Calmecac. Here, the future state elite is trained. The daughters of the nobility also have access, as priest's pupils. [male voice] This is where I first saw her. She was called Ahuic, like the goddess of the rivers. [narrator] Those who are admitted to the Calmecac have painful rituals waiting for them. [dramatic music plays] [narrator] Self-mortification and blood sacrifice to appease the gods are part of everyday school life. [male voice] Ahuic gave me strength, but the priests were not supposed to know of our love. [narrator] Contact with the temple disciples is forbidden to the young men on pain of death. The punishments of the Aztecs were draconian. In our opinion, very, very severe. But they ensured that the social system was preserved, that everyone took his place in this order and did not leave it. [narrator] State-trained and paid judges monitor compliance with these laws. Trials are public. Judgments are made jointly by the judges, and repeat offenders are punished particularly severely. Anyone caught stealing twice is liable to be stoned to death. If you are drunk in public, your head will be shorn, and you may even lose your house. Adultery is punishable by death, not only for the adulterers, but also for their confidants. There was also a concept of judicial equality, so when people came into the court, whether they were commoners or the nobility, they were treated essentially as equals. There is a strong focus on having laws and enforcing them and treating people justly. [narrator] And those who confess their offence before it is discovered can even count on forgiveness. [male voice] For Ahuic and me, everything came to a good end. We both escaped punishment by the priests. The priests gave us their blessing. In 1518, Ahuic became my wife. [narrator] Only if the highest priests agree, their disciples may give up their service to the gods and marry a man who seems suitable. Four days of celebration. The family and neighbors give the couple advice for a long marriage. The couple's garments are knotted together as a sign of the marriage bond. But even in the world of the Aztecs, not every marriage endures. There was a regulation that spouses could get divorced, and this right applied to both men and women. We don't know, of course, what the social consequences were for both spouses. But we do know that there were rules on how property was divided and who was allowed to raise the children. The girls stayed with the mother and the boys stayed with the father. [narrator] But marriage is still intended as a bond for life. Because marriage and family are of particular importance to the Aztecs. They ensure the continuity of their community. [male voice] It was a good time. The gods were good to our people. [narrator] It's a seemingly perfect world, but at a high price for the individual. The Aztec manuscripts also document human sacrifice through cruel rituals. On the altars, men's and women's hearts are cut out while still alive. Every year, tens of thousands are supposed to have found their terrible fate in this way. [Fargher] It may seem very barbaric and very violent to us today, but for them it wasn't that way. It's a different cultural context that they were living in. The relationship between humans and the supernatural is through blood, so human blood nourishes the deities, and if you nourish the deities, then they can give you life back, so death and life are reciprocal. It's not one ends the other. Each one is necessary for the other to exist. [narrator] The manuscripts describe how the skulls of the victims were literally pierced by the priests and hung on a wooden scaffolding in front of the great pyramid in the center of the city. For a long time, scientists were of the opinion that these were exaggerated representations that the Aztec scribes had to make at the behest of the Spanish conquerors as justification for their own atrocities against the Aztecs. But then, in 2015, archaeologists make an incredible discovery during excavations around Templo Mayor. A wall of human skulls almost two meters high. And they also come across the traces of the wooden scaffolding described by the Aztec chroniclers. The stakes themselves are long since weathered, but scattered everywhere: the pierced skulls. According to the Aztec view of the world, paradoxically, it was a place that gave life. For the Aztecs' great concern was that the gods might die. Therefore, one had to provide food for the sun. And how could one do that? Through human sacrifices, which feed the sun with their energy. [narrator] In the meantime, the archaeologists can reconstruct the site precisely on the basis of the gruesome finds. The size of the frame and the two towers suggest that there were indeed thousands of skulls displayed in front of the great temple. Testimony of a human sacrifice industry that is without equal. Even for the skeptics, those who believed that human sacrifice was a pure invention of Europeans, this find is the final proof that human sacrifice actually took place. [narrator] Laboratory tests of the skulls prove: 75 percent of the victims were men, most of them between 20 and 30 years of age. DNA analyses and chemical tests of teeth and bones also confirm that almost all victims came from far-flung places. They were prisoners of war and slaves from conquered provinces. The human sacrifice, apart from its religious significance, was also a demonstration of power. Especially at big feasts, the princes of the many subjugated cities were invited, and they were obliged to participate. The Aztecs offered several thousand human sacrifices to demonstrate their power and the power of their gods. [narrator] It is a nation in a permanent state of war. Shortly before the arrival of the Spanish, the Aztec dominion reaches its greatest expansion. It stretches from the Atlantic coast over the plateau of Mexico to the Pacific Ocean. The Aztecs control about six million people. From their campaigns, the Aztec fighters bring loot, tribute, and prisoners of war to Tenochtitlan, destined for slavery and human sacrifice. The system of the Aztec Empire was based on the tribute system. Tributes were paid, and without them, this huge city would hardly have been able to survive. So this applied from raw materials to the finest luxury goods. All this had to be brought in from far away, and of course, due to the tribute, the Aztec Empire was able to gain further wealth, and it created the possibilities to expand further and further. [narrator] The tributary city-states have precise requirements as to what they have to produce and how much they have to pay. It's systematic exploitation. This sheet of the Codex Mendoza shows us a very nice tribute list. It was specified exactly what the tributary city-states had to deliver. Here we find these ornate armors, but then also food, like beans, or jewelry. This was all regulated in detail, because the Aztecs attached great importance to the punctual arrival of the tributes. If this was not the case, harsh consequences were the result. [narrator] The greed of the Aztec metropolis for goods, slaves and human sacrifices increases from year to year. [Gunsenheimer] The far-reaching expansions and the tribute demands associated with them, naturally meant that many provinces had to put a heavy burden on the local population. And it brought them much closer to the limits of their economic capacity. And that of course makes such a structure very fragile, very frail. It is vulnerable. As soon as someone puts a match to it, it burns. [narrator] When Hernán Cortés and his men travel through the Aztec Empire in 1519, this moment has come. [male voice] I still remember the first time I saw them. I never thought it possible that they would betray the hospitality of our great Moctezuma so shamefully. He had given them gifts, but the white men lured our revered Moctezuma into a trap. First, they captured him. Then, they killed our Tlatoani and threw his body into the lake. [narrator] How Moctezuma actually died is still disputed. Some say that he was accidentally injured or even deliberately hurt by his own people, while indigenous sources claim that the Spaniards got rid of the useless hostage by murder. [narrator] The fact is, after the death of Moctezuma, the Spaniards have to flee at first. They try to escape over the floating gardens and embankment streets of the city. In the Noche Triste, the Sad Night, 450 Spaniards die, and only about 100 survive. It was the first great defeat of the Spanish in a battle in the New World. [narrator] But their victory does not save the Aztecs. [male voice] The gods had no mercy on our people. Many of us fell ill with a mysterious ailment. Even my poor wife. The Spaniards had brought us the fever. [narrator] Diseases introduced by the Spaniards, such as typhoid and smallpox, rage among the inhabitants of the city. The locals have no immune defense against the foreign pathogens. Within one year, almost half of the population of Tenochtitlan dies. [male voice] Ahuic couldn't watch our daughter grow up. Our end was near. [narrator] Hernán Cortés and his men were to return to the lake and plan the storming of the city with their local allies. The leaders of the tribes that were enemies of the Aztecs had excellent knowledge of the place. They besiege Tenochtitlan for three months, and starve out the people. [Fargher] After having seen the city, they developed this plan of assaulting it from the water instead of across land. They were gonna build a series of boats essentially in pieces, and then they were going to carry it across the mountains to the area. And that's how they did it. [narrator] Then the attack begins. In August 1521, the Spaniards storm the surrounded city together with more than 20,000 allied warriors. [screaming] It was not the small handful of Spaniards alone who were responsible for the downfall of the Aztec Empire, which brought down a huge empire here, but above all the fact that the Spaniards had very, very many powerful indigenous allies who fought the Aztec Empire and who tried to free themselves from the domination of the Aztec Empire. [screaming] [narrator] They fight street after street. The last Aztec contingent offers fierce resistance. Even women and children stand in the way of the attackers. On August 13, 1521, the slaughter is over. At the end of this conquest, 240,000 Aztecs are dead. Only a few manage to escape. [male voice] I got away, but our town was lost. Nothing remains but songs of pain. [narrator] The conquistadors and their allies plunder and pillage the city. Then they raze the once powerful Tenochtitlan to the ground. With the destruction of the Aztec Empire, the Spaniards lay the foundations of their colonial empire in Mexico and Central America. Their allies, however, will soon meet a new, more merciless oppressor. We don't know how long the Aztec Empire could have lasted. We know that it lasted almost a hundred years in the form in which we know it today, and that is of course a short time. And it's a tragic end, because they failed because of enemies they didn't know and had no idea how to deal with. [narrator] For the indigenous peoples, it is the end of their world. There could have been much more to come and much more to develop. But that was lost in this clash of civilizations. [narrator] The heritage of the Aztecs has been preserved for posterity in the records of their scribes. The scribes were, if you like, the memory of the Aztecs. They recorded what the Aztecs had achieved in their past. They depicted the history that this people referred to. They illustrated their strength, on which the power of this people was based. [male voice] When we die, we're not really dead. We will live. We will ascend and revive. For we are the children of the sun. [narrator] The Spanish built Mexico City on the ruins of the former Aztec metropolis. [rousing music plays] [narrator] Only with the country's independence three centuries after the arrival of the Spaniards, the awareness of the Aztec legacy is revived. Today, many Mexicans see themselves again as the descendants of the Aztecs. Their heritage is celebrated. It lives on in everyday life. In the Día de los Muertos, the festival of the dead, Aztec and Christian culture mix. The national flag connects modern Mexico with the country's Aztec roots: The eagle on the cactus with a snake in its beak. This is the founding myth of the perished Aztec empire.