Although not all are open to the public because of their difficulty of access, there are 19 rooms in the ruin which still have their original ceilings intact. In making a ceiling, the Indians used two or more main stringers—that is, large beams of pine or juniper—which they set into the walls of the room at a height of 8 or 9 feet, traversing the shorter dimension of the room. Running at right angles to the stringers, they placed cottonwood poles or splints of juniper, and, over these, reeds, rushes, or woven matting. Upon this they put adobe mud which was well packed to make a firm roof, or, if there was to be another room above it, a stout floor. Since the entire ruin has not been excavated, it is possible there may be more rooms with ceilings intact, or others in which, although the ceilings have collapsed, the first-floor walls and part of the second remain. As far as we can tell from the excavated rooms and from the surface evidence, there are 221 first-story rooms. There are intact portions of 119 second-story rooms and at least 12 third-story rooms. When originally inhabited, there were many more than the 352 rooms that we can count today. Generally, access from one room to another was by doorways that led from the back or side portions of the pueblo out toward the central plaza. However, several rooms also had lateral doorways, many of which had at one time been sealed up, either by the first inhabitants or by the second group. When burials were made in a room, it must have been necessary to seal all the doorways, unless the bodies were placed in subfloor pits or covered with dirt or debris. Among the second-story rooms in the northeastern section are four special doorways, each placed in the corner of a room so that it connects with the adjoining diagonal room. As far as we know, corner doorways occur only in second-story rooms, with the possible exception of the double doorway mentioned below. One corner doorway leads into a room that had four normal doorways, one in each side. We do not know if this room had a special function, but it was the most accessible in the entire pueblo. [Illustration: Section of wall at Aztec Ruins showing sealed door at left.] One corner doorway is possibly unique in the entire Southwest; beneath it is a second and much smaller one which led from the second-floor level into a first-floor room which could be entered only by this means. Although there is a step arrangement in this lower doorway, it is so small and its roof is so low that it must have been a matter of crawling rather than walking through it. This doorway enters the lower room so high in the wall that it would also have been necessary to have a ladder inside the room to enter or leave it.