The first great houses of Chaco Canyon: Pueblo Bonito

Great houses began to rise in Chaco Canyon, in north-western New Mexico, at the end of the Pueblo I period, when the farming villages of the Colorado Plateau were growing larger. Pueblo Bonito, at the foot of the canyon’s northern cliff, shares an arc-shaped plan with Una Vida and Peñasco Blanco, counted with it among the oldest great houses. The National Park Service dates its planning and construction in stages to about 850–1150; other accounts give 828 for its first occupation, or place the beginning of the earliest great houses around 900.

At its height Pueblo Bonito covered about 3 acres (1.2 ha) with some 800 rooms; massive walls of core-and-veneer masonry, up to about a metre thick, carried four or five storeys. A wall running due north–south divided the central plaza, with a great kiva on either side, and more than thirty other kivas have been found. The archaeologist Mary Metcalf estimated that the main building took 805,000 man-hours of work. Estimates of its population range from several thousand to fewer than 800 or even about seventy people, and many scholars see it as a ritual centre rather than a town.

Richard Wetherill and George H. Pepper excavated Pueblo Bonito in 1896–1900. Its rooms have yielded 111 cylindrical jars and, in sherds analysed in 2009, traces of cacao brought from at least 1,900 km away — the first evidence that cacao reached what is now the United States before the Spanish arrived. In January 1941 a great slab of the canyon wall, the ‘Threatening Rock’, fell on the rear of the building. Pueblo Bonito is part of the Chaco Culture National Historical Park, a UNESCO World Heritage Site.