An Urban, archaeological and topographical plan of Teotihuacan (copyright: Rene Millon). Teotihuacan was an ancient Mesoamerican city located in the Valley of Mexico, which is located in the State of Mexico, 40 kilometres northeast of modern-day Mexico City.

Teotihuacan began as a religious center in the Mexican Interior sometime at the 1st cent CE. It was home to multi-floor apartment compounds built to accommodate its large population. The term Teotihuacan is also in use for the entire civilization and cultures associated with the city.

Teotihuacan was a magnificent city of around 200,000 inhabitants in the 5th century CE being the sixth largest city in the world and the largest in the Americas of the same era.

Below, a view of the Pyramid of the Moon from the Pyramid of the Sun (wikimedia commons).