The recovered bones of martyrs slaughtered during The Terror are on display in this church crypt.

These 17th-century mummies are no longer naturally preserved, but remain on display today.

Mummified monks and the accidentally interred, in a 17th-century crypt.

This small chapel is built of human bones and decorated with a golden skeleton.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

Charnel house at the foot of Mount Sinai.

An ancient ossuary in Rouen.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

The personal charnel house of Anton Bruckner.

5,000 skulls in memorial to those killed by the Khmer Rouge.

Mysterious painted skulls in Moravia.

Thousands of well-dressed mummies below a monastery.

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

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

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.

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

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.

Structure built from the skulls of vanquished foes.

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

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

The mystery of the Putim Ossuary involves a tricorn hat.