Most of the kivas were small circular structures, about thirteen feet in diameter, with the wall set back a foot or more, some three feet above the floor, to form an encircling bench. On this bench were six masonry pilasters which helped to support a cribbed roof. The spaces between pilasters formed recesses. The one to the south was the deepest and contained the ventilator flue. The deflector, which stood between it and the center fire pit, was usually of masonry, but sometimes of wattle work. In addition to these circular kivas, which were the normal type, there were also circular or rectangular rooms with rounded corners which seem to have had a ceremonial nature, although they lacked the usual kiva features and were not subterranean, though surrounded by high walls. For the most part kivas lay in the front of the cave, but there were also some in the rear. In addition to the various rooms and kivas there were also towers, sometimes incorporated in the building-mass of the great house, and sometimes built separately. They had various shapes, including round, oval, D-shaped, and rectangular. Some were two stories high. There were doorways in the side, but no windows. There are many theories as to the use of these towers, but there are some objections to all of them. One is, that they were designed as observation posts to watch for enemies, or as fortresses. They are usually loop-holed and, when found at a distance from the dwelling, are often on easily defended points which command a good view of the adjoining terrain. This, however, is not invariably the case, for some of the isolated towers are so placed that there would be little visibility, and defense would be extremely difficult. Many are far too small to have served as fortresses. Another theory is that they may have had some ceremonial use, and may have served as solar observatories to obtain calendrical data essential in the planting and harvesting of crops and fixing of dates for religious rites connected with these activities. Some, however, are located in spots not suitable for making such observations. Across the canyon from Cliff Palace is a remarkable surface-structure known as “Sun Temple”, which some archaeologists consider an elaborate form of tower. This is an unroofed D-shaped building with double walls over twelve feet high. The space between the walls is divided into small rooms, and there are ten other rooms at the west end of the building. There is one kiva in this western section and two others in the big center court enclosed by the walls.