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

Artfully arranged bones of 5,800 Austrians.

The personal charnel house of Anton Bruckner.

Thousands of well-dressed mummies below a monastery.

Mysterious painted skulls in Moravia.

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

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.

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

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

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

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

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

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

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.

Structure built from the skulls of vanquished foes.

This curious building hides eclectic details like medieval gargoyles alongside naked angels and Art Nouveau mosaics.

What better way to honor a pioneering anatomist than by preserving his severed head like a specimen?

This 18th-century dissection theater's frescoes display a gorgeous tension between the terrestrial and esoteric.

A collection of collections, including an anatomy museum, the “Cabinet of Physics of Alessandro Volta, a museum of natural history, mineral collection, and much much more...

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