Hovenweep National Monument has a long history of human habitation, dating back to around 6000 B.C. From about AD 1166 through 1277, the area was occupied by Ancestral Puebloans, who used prehistoric masonry techniques to build a variety of structures, from ceremonial kivas to stone towers. The Hovenweep Castle and Rimrock House, shown here, are among the dozens of these structures that endure today.