While as a rule there is great similarity in secular rooms in different culture areas of the Southwest, the more archaic ceremonial rooms of these regions vary considerably. The rooms ordinarily called kivas are of two distinct types, circular and rectangular. There are two kinds of circular kivas,[38] one having pilasters and banquettes to support the roof, the other without pilasters, apparently roofless, but surrounded by high walls as if for the purpose of obscuring the view from neighboring plazas. The circular kivas commonly do not form a part of the house mass, being separated some distance from the secular rooms. From all that can be learned it appears that the round kiva is an ancient type, its position in the rear of the cave in such cliff-dwellings as Spruce-tree House and Cliff Palace indicating that this form is as old as the building itself. The circular type, with pilasters, is confined wholly to the eastern region, having been reported from the Mesa Verde, the San Juan and many of its tributaries, Chaco canyon, and certain ruins west of the Rio Grande. Circular kivas somewhat modified are found also in many of the Rio Grande pueblos, where they are still in use. A subtype of circular kivas without pilasters but provided each with one large banquette is the common form of circular ceremonial room in the Navaho National Monument and the Canyon de Chelly. The modern representative of this subtype is the Snake kiva of the Hopi, which has become rectangular, the large banquette (_tuwibi_, pl. 14) being modified into the “spectators,” or elevated surface of the floor. The corresponding ceremonial rooms at Zuñi and in the prehistoric Hopi pueblos are rectangular in form and of simpler architecture. Similarly shaped ceremonial rooms, not subterranean, are still in use in modern Hopi pueblos. As a good example of this archaic form of ceremonial room at Walpi may be mentioned that in which the Flute altar is erected and in which the Flute secret rites are performed.[39] This ancestral room of the clan is a rectangular chamber forming part of the second floor, and is entered from one side. The Flute clans came from a pueblo, now a ruin, in the north, but after union with the Ala, who lived at Tokónabi, they settled at the Snake pueblo, Walpi. So it may be supposed that their ancestors also had no special kiva, but celebrated their secret rites in an ordinary house. The fraternity of Sun priests likewise erect their altar and perform their secret ceremonies in a room, not in a kiva; so do the Kalektaka, or warriors. None of these rooms is commonly regarded or enumerated as a kiva, but such chambers are believed to be the direct representatives of the ceremonial rooms built above ground as a part of the house, in the manner more characteristic of ceremonial rooms in Arizona ruins.