The Ossario: Like El Castillo, this step-pyramid temple dominates the platform, only on a smaller scale. Like its larger neighbor, it has four sides with staircases on each side. There is a temple on top, but unlike El Castillo, at the center is an opening into the pyramid which leads to a natural cave 12 metres (39 ft) below. Edward H. Thompson excavated this cave in the late 19th century, and because he found several skeletons and artifacts such as jade beads, he named the structure The High Priests' Temple. Archaeologists today believe neither that the structure was a tomb nor that the personages buried in it were priests.