Study of the cliff dwellings of the Mesa Verde has revealed a surprising similarity of architecture throughout the area. The structures were the work of a single tribal group and a definite pattern was followed by all the members. Some cliff dwellings were small, others very large, the size depending entirely on the size of the cave. The area covered by the tribe embraced the Four Corners sections of the present states of Colorado, Utah, Arizona and New Mexico. But in all the cliff dwellings constructed by the members of this far-reaching tribe certain architectural features are commonly found. Below are shown some of the details that characterize Mesa Verde architecture. [Illustration: No. 1. Most of the doors were small rectangular openings, usually two or three feet above the floor. The average dimensions of forty doors measured in Cliff Palace were: height, 25 inches; width, 16 inches.] [Illustration: No. 2. T-shaped doors are less common than the rectangular openings, some ruins having many, others very few. The T-door is simply a standard door with the added notch at the bottom. It is a much more convenient door for if the hands are placed on the two ledges it is quite easy to fold the legs and swing through the opening.] [Illustration: No. 3. Windows are not common in Mesa Verde ruins. When present they are small, often little more than peepholes. Note the door slab leaning against the wall.] [Illustration: No. 4. Doors were closed with thin sandstone slabs. A small stick set into the masonry under the lintel kept the door slab from falling through.] [Illustration: No. 1. These small built-in shelves are very common on the inside walls of the rooms. Evidently they were for the storage of household articles.] [Illustration: No. 2. Plastered walls are extremely common, the plaster being made of clay of various colors. The wall shown here has orange-red designs on a white background. The three-triangle design is found more often than any other design element, being especially common in kiva paintings.] [Illustration: No. 3. Typical Mesa Verde masonry is made of rather large, well shaped stones, set in thick layers of adobe mortar. Small stones, or spalls, were forced into the mortar to compact it in the joint.] [Illustration: No. 4. Masonry in the cliff dwellings often exhibits surprisingly smooth surfaces and clean sharp lines. The stonework in this wall is of the highest quality.] [Illustration: No. 1. Roofs of the rooms in the cliff dwellings were constructed of poles and adobe. The covering layer of packed adobe was from three to five inches thick and was smooth and hard.] [Illustration: No. 1.