Picture Canyon, located in the Comanche National Grassland in southeastern Colorado, was named for its prehistoric rock art. There is evidence of prehistoric inhabitation of sites in Picture Canyon by Paleo-Indian, Archaic and Post-Archaic cultures, from about 12,000 years ago to 400 years ago. In addition to rock art, there are also carvings in walls that are used to identify the entry into fall and spring equinoxes.