View SW from Alto Mesa over Pueblo Bonito Anasazi multi-storey great house, Chaco Canyon, New Mexico. Shows the D-shaped plan, the open plaza symetrically divided by a N-S wall, the roomblocks rising away from the plaza from one to four storeys, and some of the dozens of kivas (circular ceremonial rooms). Largest and best known of the Great Houses in Chaco Canyon, considered the type site for the Classic Bonito Phase (AD1020-1120) of Chacoan Culture. Built in stages from early AD900s to c 1200; in its final form it covered more than three acres and comprised some 600 rooms and 40 sunken and above ground kivas. Chaco Wash, the cliff of South Mesa, and South Gap are visible to the rear. The foreground rubble is from Threatening Rock, a massive pillar detached from the North Cliff which fell onto the pueblo in January 1941. It is used as a visitor viewing point.