Teotihuacan at its Peak
Around 250 AD, Teotihuacan was one of the largest cities in the world and the dominant center of central Mexico. Located in a high valley northeast of modern Mexico City, it had grown from a modest settlement into a planned metropolis whose influence reached across Mesoamerica. Its monuments, especially the Pyramid of the Sun, still rank among the most impressive achievements of the ancient Americas.
The city's rise began in the last centuries BC. The eruption of the Xitle volcano in the Basin of Mexico likely pushed people toward the Teotihuacan Valley, though scholars debate how large a role this played. The valley offered springs, fertile land, and access to obsidian, a volcanic glass prized for tools and weapons. Control of obsidian production and trade gave the city economic strength. By the first couple of centuries AD, its population was growing rapidly, and the main ceremonial core was taking shape.
What visitors saw was a remarkably ordered city. A broad central avenue, now called the Avenue of the Dead (a name given by the Aztecs, who found the ruins centuries later), ran roughly north to south and linked major monuments. The Pyramid of the Sun, among the largest structures in Mesoamerica, was built in stages and is generally dated to the first two centuries AD. The Pyramid of the Moon stood at the avenue's northern end, and the Ciudadela complex, with its Temple of the Feathered Serpent, lay to the south. Beyond these were hundreds of apartment compounds, workshops, and markets. Estimates of the population at its height commonly range from around 100,000 to 125,000 or more, though they remain uncertain.
Teotihuacan's reach was cultural and commercial as much as political. Its distinctive architecture and pottery, and its green obsidian from the Pachuca source, turn up across Mesoamerica. Evidence at Maya sites such as Tikal suggests significant contact in later centuries, and some scholars argue for outright intervention in Maya politics. The exact nature of its power, whether imperial, mercantile, or something else, is still debated, partly because the city's own writing is minimal and no clear royal records survive.
The city remained powerful for several more centuries before declining around the 6th or 7th century, when major buildings along the avenue were burned and its central authority collapsed. Causes may have included internal unrest, economic strain, or environmental pressures. Even in ruin, the site remained sacred. The Aztecs, centuries later, revered it as the place where the gods were created, and gave the city the name by which we know it. Today it is a UNESCO World Heritage Site and a major window into Mesoamerican urban life.