The number of buildings that composed the Aztec Spring village (fig. 1) when it was inhabited can not be exactly estimated, but as indicated by the largest mound, the most important block of rooms exceeds in size any at Mitchell Spring Ruin. While this village also covered more ground than that at Mud Spring, it shows no evidence of added towers, a prominent feature of the largest mound of the latter. Two sections (fig. 1, _A_, _B_) may be distinguished in the arrangement of mounds in the village; one may be known as the western and the other as the eastern division. [Illustration: FIG. 1.—Ground plan of Aztec Spring Ruin.] The highest and most conspicuous mound of the western section (_A_) is referred to by Professor Holmes as the “Upper House.” Surface characteristics now indicate that this is the remains of a compact rectangular building, with circular kivas and domiciliary rooms of different shapes, the arrangement of which can not be determined without extensive excavations. The plan of this pueblo published by Holmes[26] shows two large and one small depression, indicating peripheral rectangular chambers surrounded by walls of rectangular rooms. [26] Op. cit., pl. xl. The author interprets the depressions, _K_, as kivas, but supposes that they were not rectangular as figured by Holmes, but circular, surrounded on all four sides by square secular chambers, the “Upper House” being formed by the consolidation of several units of the pure pueblo type. Although Aztec Spring Ruin is now much mutilated and its walls difficult to trace, the surface indications, aided by comparative studies of the rooms, show that Holmes’ “_a_,” “_b_,” and “_c_,” now shown by depressions, are circular, subterranean kivas. They are the same kind of chambers as the circular depressions in the mounds on the south side of the spring. The height of the mound called “Upper House” indicates that the building had more than one story on the west and north sides, and that a series of rooms one story high with accompanying circular depressions existed on the east side.