Preserve, southern Arizona, U.S. Established in 1918, it occupies 472 acres (191 hectares).
The site's pre-Columbian ruins are dominated by the Casa Grande ("Big House"), a multistory building topped by a watchtower built by Salado Indians in the 14th century; it is the only surviving building of its type. Nearby are partially excavated village sites established much earlier by Hohokam Indians (see Hohokam culture ).