Teotihuacan, located in the highlands of central Mexico, is one of the world's most impressive archaeological sites. Between 100,000 and 200,000 people lived there at its peak around 600 A.D., making it one of the ancient world's largest cities with an urban core covering some twenty square kilometers. Settlement began about 200 B.C. and the basic layout of the city was complete by the mid-second century A.D. Most of the major construction was accomplished within the next hundred years. In plan, Teotihuacan is a complex urban grid filled with single- and multi-floor apartment compounds. This grid, unique in Mesoamerica in its scale and organization, implies a high degree of social control. Presumably an elite group of nobles directed the building projects and coordinated trade and tribute relations with far-flung corners of Mesoamerica.
The primary avenue, the so-called Street of the Dead, runs on a north-south axis for several kilometers and aligns the city approximately fifteen degrees east of north toward Cerro Gordo. The Pyramid of the Moon, facing south, lies at the northern end of this avenue; the Pyramid of the Sun, facing west, is about a kilometer down the avenue. Another major structure, the Ciudadela, is a great sunken plaza further south. It is surrounded by fifteen smaller stepped pyramids.
Sometime during the mid-seventh century, certain sectors of the city, particularly around the Pyramids of the Sun and Moon, were repeatedly burned and sacked. The city never recovered from these attacks. The ethnic identity of Teotihuacan's inhabitants is not known. No writing system has been discovered there, even in the intricate iconography of its many painted murals. The original name of the city is not known. It was called puh (Place of the Reeds) by the contemporary Maya. Many centuries after the city's demise, it was named Teotihuacan, "Birthplace of the Gods" by the Aztecs. From its foundation in the second century B.C. to the present day, Teotihuacan has been a legendary locus of political power and a pilgrimage center of tremendous significance.