An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

A sunken idol welcomes parishioners to Davy Jones' Locker.

This former fascist summer camp was abandoned for decades.

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

Statue of a decomposing prince that once held his heart in its hand.

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

A neighborhood church's unusual abstract stained glass was the final project of avant-garde artist Jean Cocteau.

This building’s ghostly exterior reflects its former lives as a prison, school, and funeral home.

There has been an astronomical clock on this spot since the 14th century.

A sandstone block marks the alleged spot where the legendary writer was conceived.

This unusual piece of Renaissance art depicting the bodily horror of crucifixion and skin disease may have been inspired by fungus-induced hallucinations.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

This massive library holds what was once the largest book collection in the world.

Abandoned railway line circling the city of Paris.

Notorious artist squat renovated into legal studios.

France's most famous cemetery, with some of its most curious tombs.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

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

Spiral alpine structure provides an alternative experience of viewing the Matterhorn.

An unassuming Swiss institution houses Europe's largest toy museum.

A unique collection of Swiss art brut and naïve art displayed in an old warehouse.

An interactive exhibition space dedicated to the kinetic sculptures of Swiss artist Jean Tinguely.

This ossuary is more than five centuries old and is heralded as one of the finest in Switzerland.

A trove of ridiculously valuable prints and manuscripts under one roof.