Thousands of well-dressed mummies below a monastery.

Visit the ancient, mysterious Roman catacombs ... in the Netherlands.

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

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

These 12th-century catacombs carved into a mountainside were a place of mysticism and Christian hermitages.

A burial vault located under Tiber Island in the middle of the Italian capital.

These lesser-known Maltese catacombs date back over 1,700 years.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

A hidden gem in the middle of the city's infamous Jewelry Quarter.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

The Neapolitan Cult of the Dead still cares for the skulls at this mini-Fontanelle.

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

Overshadowed by other, more famous Maltese catacombs, this ancient burial chamber has one of the best examples of a ritual agape table.

This sword isn't waiting for a king to pull it out. It was placed there by a saint.

The site of the first battle of World War II.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

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

These azure waters were thought to lead to the Mayan Underworld.

There's a mini version of Iguazu Falls hidden in the Balkans, and it's got a rope swing.

This geothermal hot spring hides beneath a slowly growing mineral dome.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.