Chichén Itzá

Chichén Itzá's Temple of the Warriors, with the Pyramid of El Castillo in the background

Chichén Itzá, "the mouth of the well of the Itzás," was likely the most important city in the Yucatán from the 10th to the 12th centuries A.D. Evidence indicates that the site was first settled as early as the fifth century A.D. but was apparently abandoned thereafter. Then, in 964, the Itzás, a Maya-speaking people from the Petén rain forest around Tikal, moved into the city. Archeologists have fully explored only about 20 or 30 of several hundred buildings on the four-square-mile site. El Castillo (The Castle), a 98-foot-tall pyramid, dominates the city, while the Temple of the Warriors features murals of battle scenes and village life.

Source: http://www.pbs.org/wgbh/nova/maya/worl_sans1_02.html