In 1910, Harvard’sHar Peabody Museum Expedition of 1910 investigated, a small buried structure named Building B of Group II. It would be the first structure to be scientifically studied in the Maya lowlands. This study would produce many surprises.

It provided the first proof that the Maya built new structures on top of existing structures. It also provided the first burial found inside a structure and not just one burial but six burials containing 22 skeletons. These burials contained the first polychrome ceramics found. The large and varied selection of ceramics produced the first ceramic sequence. Yet, one hundred years later the same structure provided an additional early burial, the largest sample of Pre-Mamon ceramics in the Lowlands and a pair of large witz masks dating from 400 B.C.