The Mask Temple (Structure N9-56) was begun around 200 BC and modified several times up to AD 1300. It has two 13ft stylized masks of a man in a crocodile headdress emblazoned on its west face to the north and south of the main stairs. Dating from about AD 400, these are considered some of the finest big masks in the Maya world.
What you actually see are fiberglass replicas that have been crafted in front of the original limestone masks in order to protect them. Deep within this building archaeologists found the tombs of a man adorned with shell and jade jewelry, and a woman from almost the same date. The pair are thought to be a succession of leaders – perhaps a husband and wife, or brother and sister.