Actun Tunichil Muknal - classic Mayan archaeological site. You can see Mayan skeletons here as well as other artifacts.
Actun Tunichil Muknal (Cave of the Crystal Sepulchre), also known locally as “Xibalba” or ATM, is a cave in Belize, near San Ignacio, Cayo District, notable as a Maya archaeological site that includes skeletons, ceramics, and stoneware. There are several areas of skeletal remains in the main chamber. The best-known is "The Crystal Maiden", the skeleton of a teenage girl, possibly a sacrifice victim, whose bones have been calcified to a sparkling, crystallized appearance.