(tāōtēwäkän'), ancient commercial and religious center in the central valley of Mexico, c.30 mi (48 km) NE of Mexico City. Once thought to be the great religious center of the Toltec, it is now held to be the relic of an earlier civilization. Teotihuacán is the largest (c.7 sq mi/18.1 sq km) and most impressive urban site of ancient America. The Pyramid of the Sun, the tallest in Mexico, is 216 ft (65 m) high and covers approximately 10 acres (4 hectares) at the base; it dominates the symmetrical ground plan laid out in grid fashion along major thoroughfares, including the city's central axis—the Street of the Dead. Other buildings along this axis include the Pyramid of the Moon; the Citadel containing the Temple of Quetzalcoatl, so called because of its carvings of feathered serpents; the Temple of Agriculture; and the Quetzalpapalotl Palace.
The earliest cultural horizon at Teotihuacán dates to c.100 B.C. The culture flourished from about A.D. 300 to 900, undergoing tremendous expansion; it became the most populous city in the Americas at its height. Excavations have revealed large chambered structures resembling communal dwellings. The people of Teotihuacán brought sculpture, the art of carving exquisitely stylized stone masks, ceramic manufacture and decoration, and mural painting on walls to a high degree of refinement. The designs show a strong concern for cosmological matters, indicating the existence of a complex religious system.
More recent archaeological work at the site, as well as elsewhere in Mexico, has revealed that Teotihuacán was a commercial as well as a religious center. Craft specialization is evident in various parts of the city, and Teotihuacán influence is seen in such far-off places as the Guatemala highlands, the Maya lowlands, and the valley of Oaxaca. Some neighborhoods of the city seem to have been inhabited by groups of immigrants who retained their distinct ethnic identities. The political organization of Teotihuacán and its sphere of influence are unknown.