Seen above is an artist's rendering of what Pueblo Bonito, the largest of the great houses in Chaco Canyon, may have looked like at the height of occupation, AD 1000. Bonito was the "capital" of this valley, which contains numerous other ruins, and the surrounding 100 square miles of the Chaco Plateau. New masonry techniques allowed them to build larger structures and thus become an economic and agricultural center, storing food for use in lean times. The decline of Chaco and other ancestral puebloan cultures across the southwest may have coincided with a prolonged drought during the 1100s.