Kiva
A kiva is a room used by Puebloans for religious rituals, many of them associated with the kachina belief system. Among the modern Hopi and most other Pueblo peoples, kivas are square walled and underground, and are used for spiritual ceremonies.
Similar subterranean rooms are found among ruins in the American southwest, indicating uses by the ancient peoples of the region including the Ancestral Puebloans, the Mogollon and the Hohokam. Those used by the ancient Pueblos of the Pueblo I Era and following, designated by the Pecos Classification system developed by archaeologists, were usually round and evolved from simpler pithouses. For the Ancestral Puebloans, these rooms are believed to have had a variety of functions, including domestic residence along with social and ceremonial purposes.
Evolution of the kiva
During the late 8th century, Mesa Verdeans started building square pit structures that archeologists call protokivas. They were typically 3 or 4 feet (0.91 or 1.22 m) deep and 12 to 20 feet (3.7 to 6.1 m) in diameter. By the mid-10th and early 11th centuries, these had evolved into smaller circular structures called kivas, which were usually 12 to 15 feet (3.7 to 4.6 m) across. Mesa Verde-style kivas included a feature from earlier times called a sipapu, which is a hole dug in the north of the chamber that is thought to represent the Ancestral Puebloan's place of emergence from the underworld.