The site of Tula, Hidalgo, Mexico, is well known for its distinctive architecture and sculpture that came to light in excavations initiated some 70 years ago. Less well known is the extensive corpus of archaeological research conducted over the past several decades, revealing a city that at its height covered an area of c. 16 km 2 and incorporated a remarkably diverse landscape of hills, plains, alluvial valleys, and marsh. Its dense, urban character is evident in excavations at over 22 localities that uncovered complex arrangements of residential compounds whose nondurable architecture left relatively few surface traces. Evidence of craft production includes lithic and ceramic production loci in specific sectors of the ancient city. Tula possessed a large and densely settled hinterland that apparently encompassed the surrounding region, including most of the Basin of Mexico, and its area of direct influence appears to have extended to the north as far as San Luís Potosí. Tula is believed to have originated as the center of a regional state that consolidated various Coyotlatelco polities and probably remnants of a previous Teotihuacancontrolled settlement system. Its pre-Aztec history exhibits notable continuity in settlement, ceramics, and monumental art and architecture. The nature of the subsequent Aztec occupation supports ethnohistorical and other archaeological evidence that Tula's ruins were what the Aztecs called Tollan.