The ground plan of the ruin has the form of the letter D. The building is in two sections, the larger of which, taken separately, is also D-shaped. This is considered the original building. The addition enlarging it is regarded as an annex. The south wall, which is straight and includes both the original building and the annex, is 131.7 feet long. The ruin is 64 feet wide. There are about 1,000 feet of walls in the whole building. These walls average 4 feet in thickness, and are double, enclosing a central core of rubble and adobe. They are uniformly well made. The fine masonry, the decorated stones that occur in it, and the unity of plan stamp Sun Temple as the highest example of Mesa Verde architecture. The walls were constructed of the sandstone of the neighborhood. Many stone hammers and pecking stones were found in the vicinity. THE SUN SYMBOL On the upper surface of a large rock protruding from the base of the southwest corner of the building a peculiar depression, surrounded by radiating ridges, was found. To primitive minds, this may have appeared as a symbol of the sun and, therefore, deemed an object of great significance, to be protected as a shrine. This natural impression may have prompted Dr. Fewkes in the naming of this ruin. ARCHITECTURAL FEATURES There are three circular rooms in Sun Temple which from their form may be identified as ceremonial in function, technically called kivas. Two of these, free from other rooms, are situated in the plaza that occupies the central part of the main building, and one is embedded in rooms of the so-called "annex." Adjoining the last mentioned, also surrounded by rooms, is a fourth circular chamber which is not a kiva. This room, found to be almost completely filled with spalls or broken stones, perhaps originally served as an elevated tower or lookout. The kiva that is situated in the west section of Sun Temple has a ventilator stack attached to the south side, recalling the typical ventilator of a Mesa Verde cliff kiva, and there are indications of the same structure in the two circular chambers in the court. These kivas, however, have no banquettes or pilasters to support a vaulted roof, and no fragments of roof beams were found in the excavations made at Sun Temple. East of Sun Temple, where formerly there was only a mound of stone and earth, there were found the remains of a low circular structure of undetermined use. Most of the peripheral rooms of Sun Temple open into adjoining rooms, a few into the central court, but none has external openings. Some of the rooms are without lateral entrances, as if it were intended to enter them through a hatch in the roof.