Detail of an early construction phase of Temple 33, where the inset corners so characteristic of the Petén architectural style can clearly be seen. Earlier phases of Temple 33 (including two huge stone-and-stucco masks that can still be viewed by entering a tunnel) were uncovered by archaeologists of the University of Pennsylvania project when they decided to dismantle the very damaged last construction phase of the once towering structure. Arguably the most famous find made at the extensive excavation work that was carried out on Temple 33 is king Siyaj Chan Kawiil's Stela 31, which was found ritually re-erected, terminated and then buried deep inside the last construction phase of this important Central Acropolis building.