Skeletons dressed in extravagant 18th century royal costumes cavort in the aisles of this German basilica.

The mortal remains of an estimated 70,000 people lie in the basement of a monastery in Lima, Peru.

The remains of 40,000 humans, meticulously stacked in a tiny churchyard shed.

One of the largest ossuaries in Spain is packed from floor to ceiling with bones.

This Peruvian bone silo lined with hanging human skeletons and hundreds of skulls is topped with a remarkable Michelangelo replica.

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.

This German bone house contains the remains of some 20,000 souls.

A house of bones — but nobody is quite sure to whom they belong.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

In 1830, cemetery workers in Cham unearthed a chamber housing thousands of skeletal remains from the 13th century, which can still be viewed today.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

A 1,000-year-old church holds the bones of the Christian martyrs who died hiding inside it.

In a small churchyard in Dingolfing, Germany the quaint Schusterkapelle is there to remind you of your imminent mortality.

The mystery of the Putim Ossuary involves a tricorn hat.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

An Austrian house of bones filled with hundreds of intricately painted skulls.

Structure built from the skulls of vanquished foes.

A 400-year-old mummified arm dangles from the ceiling of St. James the Greater, serving as a warning to thieves.

A collection of anatomical samples from one of the first anthropologists to suggest that humans reached North America by crossing the Bering Strait.

Europe's second largest ossuary wasn't discovered until 2001.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

A church of bones, decorated with 40,000 human skeletons.