Also since Morris’ time, the rooms through which you may now pass, and which lie between the plaza proper and the rooms with the intact ceilings, have been partially excavated in order to allow you easier access to the plaza. Finally, as part of the stabilization program, the remaining rooms in the south wing which enclosed the plaza, and which were largely composed of cobblestones, were cleared and stabilized. Morris also excavated a few rooms in the East Ruin simply as a test to see if it belonged to the same general period as the larger ruin in the west. From his findings there he felt that the East Ruin was erected during the Mesa Verde phase of Aztec. In recent years, one other major excavation has been undertaken at Aztec. This was the complete clearing and stabilization of the circular structure to the north of the ruin known as the Hubbard Mound—a massive, circular, triple-walled structure, with underlying scattered remains of earlier structures. Two heavy radial cobblestone walls now extend to the south of the main structure, and excavations revealed remnants of other heavy walls disappearing under the road to the west. This indicates that the building had originally been one corner of a group of structures. The main part of the Hubbard Mound consists of three concentric circular walls; the spaces between the outer two rings are partitioned into rooms. There are 8 rooms in the inner circle, including an entrance room on the south, and 14 in the outer, if you again count an open passageway on the south side. Interestingly enough, the three circular walls are heavier and extend deeper into the underlying sand than do the partition walls, and therefore were constructed first as continuous circles. Within the innermost circle there is a standard, small-type kiva. Evidently the entire structure represents a building for the use of a highly specialized religious organization. Part of the construction is of sandstone blocks, part is cobblestone, and all of it seems to have been generously plastered with adobe mud. There are other examples of tri-walled structures in the Southwest, but they are not very numerous and the exact uses to which they might have been put are unknown. An analysis of materials found during the excavation of the Hubbard Mound reveals that it belonged to the Mesa Verde phase.