A number of other southwestern areas in the National Park System have been established for the protection of prehistoric structures. These include Mesa Verde National Park, in southwestern Colorado, and the following national monuments: Aztec Ruins, Chaco Canyon, and Gila Cliff Dwellings, in New Mexico; Canyon de Chelly, Casa Grande, Montezuma Castle, Navajo, Tonto, Tuzigoot, Walnut Canyon, and Wupatki, in Arizona.