Pollack, who did fieldwork under the auspices of the Carnegie Institution of Washington in 1932-1940, writes: "This is the great pyramid temple at the southern end of the South Group. It will be noted that Morley (1910) indicates, on his early plan of the group, a series of rooms at two levels, across the western side of the pyramid, whereas on his map he shows rooms on the south and east sides as well."
Pollock, H.E.D. The Puuc: An Architectural Survey of the Hill Country of Yucatan & Northern Campeche, Mexico. Memoirs of the Peabody Museum 19. Cambridge, Massachusetts. Peabody Museum of Archaeology & Ethnology 1980.
Pollock then quotes from Morley's diary, a copy of which is in Peabody Museum of Harvard University:
"We crossed west in front of the South Temple at the level of the court just north of the South Temple and then skirted south along the west side of the South Temple. Here the two ranges of rooms, one behind and above the other, show, as in my map of the South Group, along the west side of the South Pyramid.
But here came the second discovery of the morning. This double range of rooms, one higher than the other, continued clear across the south face of the South Pyramid and then turning northward at the southeast corner continued clear across the east face of the Sotth Pyramid to where it joined the southwest corner of the Great Pyramid."
Sylvanus Griswold Morley, A Group of Related Structures at Uxmal, Mexico, Archaeological Institute of America, 1910.