Prehistoric, usually multistoried house of the ancestors of present-day
The use of hand-hewn stone building blocks and {{link=adobe">adobe mortar in these communal dwellings was unexcelled even in later times. Rooms on upper levels could be entered either by doorways from adjoining rooms or by ladders through holes in the ceilings; ground-floor rooms could be entered only through the ceiling. It is thought that the cliff dwellings were built as a defense against invading Navajo and Apache tribes. They were deserted by the inhabitants around the end of the 13th century. Many ruins remain, including notable ones at Canyon de Chelly National Monument , Mesa Verde National Park , and Montezuma Castle National Monument .