Teotihuacan

Teotihuacan was the greatest city the Americas had yet seen — a planned metropolis in the Valley of Mexico, laid out along the Avenue of the Dead and dominated by the colossal Pyramids of the Sun and Moon. At its height it housed over 100,000 people, drew tribute and migrants from across Mesoamerica, and influenced cultures as far as the Maya lowlands. Then, around 550 CE, its monumental core was deliberately burned, the city declined, and within a century it was largely empty. Whether the cause was internal revolt, drought, or invasion is still debated. The Aztecs, finding its ruins centuries later, believed the gods had been born there.