The walls of Montezuma Castle are formed from rough chunks of limestone laid in mud mortar which was probably made from pockets of clay found in the vicinity. After the clay was pulverized and mixed with river sand and water, it made an excellent mortar. The walls average about 12 inches thick throughout the building and are curved to conform to the arc of the cave in which the Castle rests. Walls were constructed on the very edge of the ledges with enough earth fill behind to provide level floor space. Since most of the building material had to be carried up from the base of the cliff, the individual building stones were rather small, usually no larger than two bricks. The walls were covered with mud plaster, both inside and out. Most of this has weathered away on the outside, but the plaster is well-preserved inside. In some places, finger marks of the original builders may still be seen. Rooms have an average of about 100 square feet of floor space. The smallest room is in the second story with 37.5 square feet of floor space, and the largest is in the fifth story with 240 square feet. What is now the fifth story is in the deepest part of the cave and apparently was the first part of the Castle to be constructed. At this point the cave extends in from the face of the cliff for 33 feet. Solid rock forms the roof and back wall of the room while the ends and outside wall are of masonry construction. This room is almost too large to have been a dwelling because it would be hard to heat in winter, but it might have been intended for joint occupancy by 2 or 3 families—perhaps while other, smaller rooms were being built. The Castle was constructed by people who had no metal tools of any kind. Their picks were pointed stones about as long as an adult’s hand, and their stone axes were about the same size. A shallow groove was ground three-fourths of the way around these implements; then a short stick handle was bent in a J-shape and lashed on over the groove. Some of the roof timbers still bear chopping marks. With each stroke of the ax the Indian made little progress, and cutting a large timber must have consumed considerable time. Some logs are about 1 foot in diameter and up to 10 feet in length. Ropes were probably used to pull the timbers into place since fragments of fiber ropes have been found in the excavations. Without pulleys, great physical effort must have been required to lift the logs into the cave. Resting on the main rooftimbers and laid at right angles was a covering of poles and over this a layer of coarse grass or willows. On top was placed a layer of mud 3 or 4 inches thick. Most of the original mud floors have been worn out by early visitors. [Illustration: _Vertical cross section of Montezuma Castle._] [Illustration: _Floor plan of Montezuma Castle._] [Illustration: _A doorway in Montezuma Castle._] [Illustration: _Smoke-blackened ceiling in Montezuma Castle._]