"Artists decorated the outer facades of the temples whith huge plaster reliefs modeled on the roof combs, the entablatures, and on the piers between the doors. Unfortunately, only the sculptures of the Temple of the Cross entablature remain legible. These depicted frontal views of great Witz Monsters gazing out from all four sides of the roof. The Maya thought of this temple as a living mountain. Thus, its inner santuary was "underground" because it was in the mountain's heart."
Linda Schele and David Freidel, A Forest of Kings: The Untold Story of the Ancient Maya, p. 239
Drawing by Linda Schele, © David Schele, courtesy Foundation for the Advancement of Mesoamerican Studies, Inc., http://www.famsi.org