After leaving Ruin Canyon the Old Bluff Road takes a southerly course, passing through the cedars until a sagebrush clearing replaces the “timber,” where it crosses two well-preserved Indian reservoirs, or bare surfaces of rock, dipping south, the southern border having as a retaining wall a low ridge of earth to hold back the water. The retaining wall of the second reservoir has been built up by stockmen and, when the author was there, contained considerable water. Crossing the second reservoir a trail turns east or to the left and follows the road to Keeley Camp, near which are the “Keeley Towers.” At present an automobile can approach within a mile of these ruins. SQUARE TOWER CANYON To reach the Square Tower Canyon (pls. 11-17) one returns to the reservoir on the Bluff Road and continues east about 3 miles farther, where a signboard on the left hand indicates the turn off to Square Tower Canyon. Following the new direction about southeast the great buildings are visible a mile away. An automobile can go to the very head of this canyon and a camp can be made within a few feet of Hovenweep House. If the visitor approaches Square Tower Canyon from the McElmo, he passes through Wickyup Canyon, where there are two towers on the summits of elevated buttes, not far from the junction of the canyon and the Yellow Jacket. The castles and towers in Square Tower Canyon have been known for many years and have been repeatedly photographed.[46] [46] Among the older photographs seen by the author are those of W. H. Jackson, prints of which are on exhibition in the State Historical Museum at Denver, Colo. Several descriptions of these ruins have been printed, but no satisfactory studies of their structure have been published. They are recognized as prehistoric and are generally thought to have been inhabited contemporaneously with the cliff-dwellers of the Mesa Verde, being built in the same style of architecture. CLASSIFICATION OF RUINS IN SQUARE TOWER CANYON The ruins in Square Tower Canyon are classified for convenience in description as follows: (1) Ruins which have indications of inclosed circular kivas, with mural pilasters and banquettes, and closely approximated surrounding rooms. To this class belong ruins 1, 2, and 10. Of these, Unit type Ruin (No. 10) has only one kiva and belongs to the simplest or unit form of the pure type. Ruins 1 and 2 have two or more kivas and are formed by a union of several units, combined with towers and great houses. (2) Ruins, the main feature of which is absence of a circular kiva. The Twin Towers belong to this second or “great house” type. The few cliff-dwellings in this canyon are small, generally without kivas, resembling storage cists rather than domiciles. HOVENWEEP HOUSE (RUIN 1)