In 1849, a U.S. Army expedition in New Mexico came upon the first monumental stone ruins ever discovered in North America. By the 1920s, excavations had revealed the remains of a remarkable community, constructed entirely of mortarless masonry, which flourished nine hundred years ago in the Chaco Canyon. The community, Pueblo Bonito, was in fact a township, which included 800 living and storage rooms, as well as several large kiva: underground, circular ceremonial chambers. Archaeologists have traced the growth of Pueblo Bonito, on the basis of masonry techniques, pottery designs, and tree-ring dates, and have concluded that the settlement grew rapidly within a few hundred years.
