Excavation of the badly ruined Str. E-VII revealed a well-preserved earlier platform underneath, thereafter dubbed E-VII-sub. This substructure dates from the Late Preclassic era, and at the time of its discovery it was the earliest building known from the Maya lowlands.
The terraced surfaces of E-VII-sub were completely covered with lime-based plaster, as were its four stairways and sixteen side masks, two at each side of each stairway. These masks seem to depict cosmological themes similar to those found on Str. 5C-2nd at Cerros, in Belize, a center that reached its apogee in the Late Preclassic...Since E-VII-sub's discovery, several buildings of the same age have been excavated, including the larger Lost World Pyramid at Tikal and Str. 5C-2nd at Cerros.
Robert Sharer, The Ancient Maya, p. 181-2