"Teotihuacán, Mexico... a 2,000-year-old megacity built around one of the largest pyramids on the planet." "Teotihuacán is remarkable and unique." "The scale of it, its degree of planning are really phenomenal." "Today, teams are investigating inside the city's many pyramids, revealing gruesome discoveries..." "We think they are buried alive." "...and unearthing hidden treasures." "But what were these massive pyramids for?" "Who built them?" "And why was this once-great city abandoned just 900 years after it was built?" "Blowing the pyramids apart, we'll reveal the hidden clues inside these ancient wonders... their secret tunnels and sacrificial burial chambers, exposing the dark secrets at the heart of this mysterious city. captions paid for by discovery communications" "the ancient city of Teotihuacán... an archaeological gem in the heart of Mexico." "Incredibly, this single site was once home to 100,000 people." "Giant pyramids tower over the city center, lined up along a central Avenue." "The remains of government buildings sit alongside, surrounded by the homes of the elite." "And in the fields beyond lies evidence of ancient suburbs that stretch out for miles." "This sprawling Metropolis was built 1,000 years before the ancient Aztecs Rose up." "But nobody knows for sure who the Teotihuacáno were or why, just 900 years later, this civilization seemingly vanished." "Teotihuacán was the biggest city in the Americas in the first half of the first millennium." "But there's still a lot we have to learn about the Teotihuacános." "Today, teams of archaeologists use advanced scanning and forensic technologies to reveal hidden clues and unearth Teotihuacán's deepest secrets." "David Carballo has been studying this ancient civilization for 18 years." "He believes the best way to understand who the Teotihuacáno were is to explore the city's ritual landscape that flanks its main road... the street of the dead." "You have to imagine, back in classic period times... 1,500 years ago or so... there probably would have been people gathered in the street of the dead, and from just about anywhere in the city, you could see rituals." "The most important ritual structures on the street are Teotihuacán's three massive pyramids." "The largest is also the oldest." "The ancient Mexicans built this vast shrine around the time Jesus was alive, and some believe they dedicated it to the sun." "The pyramid of the sun is a man-made mountain clad in a layer of cement and stone which gives shape to its rough heart." "Millions of tons of earth and sand pile up layer upon layer." "On the outside, 248 cut stone steps lead all the way to its towering peak over 200 feet above the city." "The sheer scale of this stone Goliath shows just how important religion was to the mysterious civilization that founded this city." "David believes the ancient Mexican priests climbed the pyramid at key times in the celestial calendar so they could be closer to their sun god." "So, we are now at the summit of the sun pyramid." "We're on top of the world, as far as that goes, right here in the Teotihuacán valley." "The sun pyramid would have been one of the most spectacular monuments of the ancient world." "We have a lot of imagery that's suggestive of fire rituals happening in the sun pyramid... the sorts of rituals which would not only commemorate big calendar endings but also some sort of accession-to-office events." "So, it would be a real place of spectacle and pomp." "The earliest Teotihuacáno needed height to worship their god, but, surprisingly, the pyramids built by later generations were relatively short." "Why?" "David believes that the Teotihuacáno were a civilization capable of significant cultural change, including the invention of a new cult to worship a different god." "This is the feathered serpent, which gives the pyramid its name." "You can see the rattle elements, telling you that this is a rattle snake, and then also the feathered elements on the body, that this is the feathered serpent." "The Teotihuacáno came to believe that the feathered serpent created the world." "And in 200 a.d., to honor their newly-elevated god, they constructed a work of unsurpassed complexity." "Teotihuacán is the origins of this god, at least as a primary god, who completely decorated a pyramid." "And what it really represents is a new effort on part of the Teotihuacán to highlight this god." "The outside of the feathered serpent pyramid is stunning, but it's the inside that truly takes the breath away." "Instead of a simple pile of mud, the core of this building is a complex, man-made honeycomb of rock and mortar." "Five distinct layers of construction are bound by thick walls." "Rubble fills the spaces between, creating modular cells." "They come together to make huge, solid building blocks." "This advanced design suggests the Teotihuacáno's building skills were evolving in step with their changing religion." "But why did they create such complexity in a part of the pyramid that would never be seen?" "David believes the reasons were practical, not ceremonial." "The geometric design made the core of the pyramid super strong." "The ancient Mexicans could then cement over 400 giant, carved heads to the outside without the whole structure collapsing." "These are beautiful sculptures, and the fact that there are so many of them on all four facades of this building attest to the immense amount of labor that went into constructing this monument." "The feathered serpent pyramid displays precision engineering." "To build this complex modular design, the Teotihuacáno had to create a completely new way of constructing their pyramids, using four distinct building materials." "The first material was wooden posts, used to Mark out a precisely aligned grid and create a sturdy scaffold." "Then they clad this wooden skeleton with mud, mortar, and volcanic stone to build a honeycomb of strong structural walls." "They packed the cells with more volcanic rock... super strong, but too rough to be used on the outside of the building." "Finally, the reserved their finest material for the exterior..." "high-quality slabs of stone decorated with elaborate sculptures." "This new religion of the feathered serpent was ground-breaking and incredibly significant, going on to influence both the Mayan and Aztec civilizations." "It is at Teotihuacán where we see the major origins of this cult to this deity, who then becomes important within mesoamerica." "Invigorated by their new religion, the Teotihuacáno put their advanced building skills to good use." "They provided their growing population with a perfectly geometrical city grid of buildings and homes." "And deep below the pyramids, archaeologists have also discovered secret tunnels." "Could these be evidence of a bloody ritual practice?" "In Mexico, investigators are unraveling the secrets of a 2,000-year-old mystery... why was the ancient pyramid city of Teotihuacán built?" "Archaeologist Sergio Gómez Chávez is searching the city's giant pyramids for clues." "He believes one key is to understand how they were used." "The largest pyramid in Teotihuacán hides a surprising secret." "Directly beneath the pyramid of the sun, archaeologists unearthed a tunnel in the bedrock." "First, they thought it was a natural cave, until they hit a carved-out chamber and beyond it, the remnants of 17 thick, man-made walls built to block access to the tunnel." "At the very end of the tunnel, they found an elaborate chamber carved in the shape of a clover." "Whatever this subterranean vault was designed to hold, it was meant to be locked away for eternity, buried under millions of tons of rock." "Now the tunnel lies empty." "Ancient robbers most likely stripped it bare hundreds of years ago." "But the discovery under the sun pyramid was just the beginning." "Hola." "Today, Sergio is exploring a tunnel he's recently uncovered under the feathered serpent pyramid." "This time, the tunnel appears untouched by thieves." "Sergio and his team have had to remove 1,000 tons of soil." "It was probably put there by the Teotihuacáno to seal the tunnel." "But the effort has been worth it, because, under the debris, he's found a treasure trove of ancient artifacts." "Today, the team is carefully removing soil from two ancient pots." "After 2,000 years in soil, the ceramic is incredibly fragile." "Sergio has already uncovered thousands of artifacts like this one." "Marks on the pots offer tantalizing hints of how they were carried." "Sergio believes that all these rare objects are offerings to the gods." "But was this tunnel a tomb... like those inside the ancient Egyptian pyramids... or a shrine?" "So far, Sergio has found no evidence of human burials." "And dark marks at the very end of the tunnel suggest this apparent dead-end looked very different in the past." "The first section of the tunnel runs nearly 50 feet under the pyramid to a cross-shaped chamber beneath the steps." "But then it cuts down again, into the bedrock, towards the center of the pyramid, and opens out into a second, much deeper chamber." "Sergio believes the marks reveal this chamber was once filled with water, making it a religious shrine, a gateway to the gods of the underworld." "Today, the water table is over 50 feet below ground." "2,000 years ago, it was much higher, filling the final chamber with water, forming a subterranean lake... a replica of the mythical underworld... where the Teotihuacáno would make offerings to the gods." "The ancient Mexicans even placed fool's gold in the walls of the tunnel, which re-created the night sky when they passed with their torches." "Tunnels under the pyramids have taught historians much about the religion of the Teotihuacáno and perhaps why the pyramids were built." "But high above the tunnels, excavations into the main body of the pyramids have revealed a darker secret..." "human remains." "Who were these people, and could they be proof of ritual sacrifice?" "Archaeologists at Mexico's largest ancient city are slowly assembling the pieces of a monster puzzle." "The once-powerful civilization that built these 2,000-year-old pyramids disappeared without a trace." "They left little evidence of who they were and how they lived." "Anthropologist Saburo Sugiyama is examining bones unearthed from the ancient city of Teotihuacán." "Saburo believes these bones may be evidence of gruesome human sacrifice." "The biggest clue comes from how these bones were found." "Archaeologists stumbled across them while tunneling deep inside the body of the pyramids." "Within the feathered serpent pyramid, inside the central cell, is a dark secret... 20 skeletons, almost completely intact, carefully arranged in what looks like a symbolic pattern." "And they're not alone." "In total, over 260 bodies are built into the fabric and foundation of the building." "The pyramid is a mass grave." "A truly gruesome find." "But the dead can yield valuable clues to the civilization that lived here 2,000 years ago." "Who were these people built into the pyramid?" "Saburo hunts for telltale traces among the bones." "Saburo believes the jaw-bone necklace is a war trophy and marks the man as a soldier." "The skeleton was found with a further 89 soldiers split up into groups of 18." "And there's more." "At the center of the pyramid lie the 20 carefully arranged bodies." "They are surrounded by precious possessions, suggesting they were members of the social elite." "In long trenches on either side lie two rows of 18 soldiers flanked by rows of eight women." "The pattern repeats around the edge of the pyramid... rows of necklaced soldiers, bordered by rows of women." "A cross-section of society entombed in what looks like a sacred symmetry." "But is this simply a graveyard, or were these people ceremonially murdered?" "Saburo searches the bones for evidence of human sacrifice at Teotihuacán." "Incisions on the jaw show that the Teotihuacános slit the throat of this sacrifice." "And there's evidence of even more gruesome execution practices." "Some of these victims may have been buried alive." "260 people in total were sacrificed to build the feathered serpent pyramid." "But were these people local or outsiders?" "Saburo finds answers by analyzing the bones of the dead." "Throughout our lives, the water we drink is locked inside the chemistry of our growing teeth and bones." "And because water alters from place to place," "Saburo can extract the ancient chemicals to work out exactly where these people grew up and lived." "Some of the high-status skeletons seem to be from Michoacán, 250 miles away, the soldiers with jaw-bone necklaces from Guatemala, 900 miles away." "Saburo believes that these victims may have been sacrificed because they were outsiders." "So, why would anyone travel up to 1,000 miles to Teotihuacán with the threat of bloody sacrifice waiting for them?" "But what was the source of this city's immense wealth?" "Strange artifacts arranged alongside the sacrificed could offer clues." "2,000 years ago," "Mexico was home to a thriving, Cosmopolitan city." "But where did the wealth come from to build its pyramids and vast urban spread?" "Archaeologist David Carballo finds fragments of an unusual volcanic glass called obsidian all over the city." "Today, he's hunting down a local source for this rare rock." "It has this beautiful, golden-green hue to it." "It's a tremendous volcanic glass, and the Teotihuacános used it for making tools, weapons." "This was their primary cutting stone." "The massive amount of obsidian found in Teotihuacán suggests it was a hugely important commodity." "Buried within the feathered serpent pyramid, alongside the hundreds of bodies sacrificed here, archaeologists found thousands of obsidian objects... arrow points and spearheads and razor-thin blades." "Perhaps workmen's tools, but none show any signs of use." "And, at the center, a collection of mysterious figurines." "These obsidian pieces weren't the personal possessions of the dead, but ritual items made especially as an offering... a clue that this civilization prized obsidian above all else." "David suspects the city's economy was boosted by a vast local supply of top-grade obsidian glass." "His colleague, Alejandro Pastrana, is tracking down evidence of ancient passages inside this modern obsidian mine." "So, these were carved out a long time ago?" "Yes." "Like in Teotihuacán times?" " In Teotihuacán times." " Uh-huh." "Alejandro guides David to an obsidian seam he believes was mined by the Teotihuacáno." "Wow, that's a great piece." "A block." "Yeah, so, it's that green-gold hue, and just look where it's freshly struck." "Perfect glass." "Can you find this quality all across Mexico?" "Mm-hmm. so, this is one of the major sources of obsidian for Teotihuacán?" "David believes the obsidian found here produced the finest blades in mesoamerica." "The Teotihuacáno had exclusive access to the source and grew rich by mining and crafting the rare glass into valuable tools for export." "One, two..." "So, this is very brittle and sharp, and you can see how clean these edges are." "The Teotihuacáno used rocks to tap obsidian blocks." "Get the angles right, and the glass fractures off into smaller and sharper sections." "And, eventually, you could make something like a knife or a really large spearpoint out of this." "This is the sharpest edge that you can get in nature." "Just cutting leather like that." "It's like a knife through butter." "So, this is sharper than surgical steel." "The ancient Mexicans didn't know how to forge metal." "They relied on obsidian for simple blades and weapons." "There's no question that this was part of the backbone of Teotihuacán's economy." "David believes Teotihuacán was a trading hub for the mining and manufacture of obsidian blades." "But this miracle blade did have a limitation... one that made the people here even richer." "The fact that it's brittle and it loses its edge quickly means that there was continually a market for it." "Obsidian's fragile nature super-charged the market for this precious resource." "David has found evidence that suggests obsidian workshops operated right across the city." "Craftsmen would have been in constant production, making a steady stream of replacement obsidian tools and weapons." "The Teotihuacáno had so much obsidian, they could export their tools and weapons far and wide." "They started building roads to reach distant cities, always choosing the fastest path and letting nothing stand in their way." "They established a huge trade network, spreading their obsidian over 1,000 miles from the Atlantic to the pacific." "As demand for obsidian grew, more and more people came to the city, and its population exploded." "Obsidian bankrolled the city of Teotihuacán." "But who were the local ruling kingpins, filling their coffers with cash?" "This recent discovery..." "a bizarre family of statues... offers a vital new clue." "Mexico's mysterious pyramid city is slowly giving up its secrets." "Grisly finds have revealed this place was built on human sacrifice, and thousands of locally crafted blades show how the city was bankrolled." "But for decades, archaeologists were stumped as to who ruled the Teotihuacáno." "Were they a monarchy, like the Aztecs and Maya?" "For archaeologist Julie Gazzola, local design suggests a different story." "Teotihuacán imagery shows religious icons and everyday life, but there are no images of royalty." "So, who was in charge here if it wasn't a monarch?" "Julie believes a recent find from under the feathered serpent pyramid could be a crucial clue to solving this mystery." "Buried under 1,000 tons of rubble, 40 feet beneath the pyramid, in the heart of the most sacred place in Teotihuacán, archaeologists found four green stone statuettes... three women and a small naked man." "Two of the figures stood under the apex of the pyramid, looking up towards the sunrise." "These simple statues are priceless pieces in an archaeological puzzle." "Perhaps they are direct links to the rulers of Teotihuacán." "Julie believes the ritual location of the statues suggests they are offerings to the gods of the underworld." "The figures are unique." "More treasures were found alongside the statues." "Julie believes all these ancient relics were commissioned and placed in the tunnel by the leaders of Teotihuacán to celebrate the birth of the city out of the sacred underworld." "For Julie, it's the exotic green stone used to produce these luxury objects that gives her the biggest clue to who the rulers were." "The Teotihuacáno made many of their ritual pieces from foreign green stones." "Julie believes these imported goods prove that an elite group of Teotihuacán traders got so rich they were able to take control of the city." "The entire place was ruled by businessmen and women in place of kings and queens." "Buildings surrounding the pyramids give an indication of the extravagant life of the city's leaders." "This elite lived and governed among the many pyramids and temples at the very heart of Teotihuacán." "Single-level structures built around a central courtyard provided spacious accommodation for wealthy traders." "The elite could afford to cover the rough stone walls in expensive lime plaster and decorate them with elaborate murals." "But over a mile away, on the outskirts of the city, the poor built their own dwellings using only the cheapest materials." "Graves discovered underneath these workers' huts reveal a life of extreme poverty for those at the bottom of the social pile." "Horrendous living conditions likely caused malnutrition, infection, and early death among the poor." "In this city of traders, the wealthy had the power, and the poor were starving and desperate... the perfect cocktail for civil unrest." "Could these scorch marks... recently discovered on the city's wealthiest buildings... finally reveal the secret to the fall of Teotihuacán?" "2,000 years ago," "Teotihuacán was the largest and busiest city in the Americas." "Over 100,000 people lived here, from the super-rich ruling traders in the center to the dirt-poor workers in the outskirts." "Investigators dating artifacts found inside the city believe that this once-great civilization shut down suddenly after just 900 years." "But why?" "Archaeologist David Carballo believes a crucial clue can be found at the most ornate building in Teotihuacán, the feathered serpent pyramid." "Here, we have feathered-serpent heads sculpted out of stone." "They're tenons, meaning they would have stuck into the facade of the building." "Originally, there were over 400 pristine heads." "But at the back of the pyramid, the sculptures look very different today." "So here, on this one, you can see that it's been defaced by knocking the snout off." "So, this one, too, seems to have been heavily damaged in the snout." "David believes the damage to the heads is so similar, it's suspicious." "This damage doesn't look accidental." "It's always the snouts that are knocked off, and so if you expect these to have sort of fallen haphazardly, you would expect breakage on other sides." "So, that suggests that there was some sort of cataclysmic event, like some sort of factional dispute, conflict, or maybe even a civil war." "But was this conflict limited to a religious feud at the feathered serpent pyramid?" "David searches the ruins of nearby elite buildings for further clues of destruction." "Well, if you look over here, this has the original white-and-red stucco motifs... these interlocking-scroll motifs." "But then you see the soot marks right here in the corner that would have been from burning these structures." "David is convinced these scorch marks are clear signs of deliberate arson, and he finds them on just about every building in this part of town." "This is where there likely was some sort of wooden beam... a support beam for the roof." "And since that was wood, with the burning, you ended up with this blackening with soot in the stucco." "The layers of ash and burnt wood suggest a massive fire raged in the center of the city." "The fire consumed all the elite and religious buildings." "There's burning in multiple rooms, in multiple palatial and temple compounds." "It suggests that this was a planned and coordinated event." "I think this is really compelling evidence that those structures that were most associated with state power... be that religious or political... were targeted disproportionately in the burning of the city." "If this destruction was deliberate, who did it?" "Was it an invasion by a rival civilization, or was this an inside job?" "A crucial clue lies a mile from the center of Teotihuacán, in a field of scattered debris that was once the workers' suburbs." "What we found out here in our excavations is that there's no evidence of the sort of burning that we see in the center of the site." "So that, to us, suggests that this isn't an attack from the outside." "Rather, the collapse happens from the inside out." "David believes the impoverished workers" "Rose up against their rulers in a social revolution." "These people, who were the working-class backbone of the city's economy, felt like the system was failing them, and so because of that, they rejected the system, and they took up arms and decided to sack their own city." "In the 7th century, the disenfranchised poor rebelled." "They burnt the city center in an inferno of heat and destruction." "With the ruling elite of traders wiped out, the city quickly fell into decline and was eventually abandoned." "Teotihuacán is remarkable in terms of world history." "It was a huge political capital, a huge economic hub, and also a pilgrimage center." "And after the collapse, there's really nothing like Teotihuacán in mesoamerica." "Although the city had died, the legend of Teotihuacán lived on." "It influenced the famous Maya civilization, and the Aztecs were so in awe of this place, they believed it could only have been made by the gods themselves." "Today, archaeologists are slowly uncovering the secrets of this ritual landscape, with its hidden chambers, ceremonial tunnels, priceless buried artifacts, and gruesome pits filled with the bones of immigrants tragically drawn to this city of dreams." "What amazing secrets could still lie locked inside the heart of this... the oldest megacity in the Americas?"