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

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

A former top secret nuclear fallout shelter now operates like a hotel stuck in the Cold War.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

A floundering Polish shipyard was once the soul of the Solidarity movement that capsized communism.

Terrifically morbid cemetary and site of famous Paracelsus' grave.

The mental institution where Van Gogh created some of his most famous work now allows guests to walk in the artist's footsteps.

A former ironworks that was the first UNESCO industrial site.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

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

This Italian stadium makes liberal use of fascist statuary to evoke classical sporting arenas.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

A sculpture serving as an homage to Pope John Paul II.

This quaint Hungarian railway system is operated exclusively by children between the ages of 10 and 14.

Possibly the world's largest hourglass only needs to be reset every New Year's Eve.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

This Communist-era residential block is one of the longest residential building in Europe.

Museum dedicated to "the man who moved the Earth."

"Portugal's Stonehenge" is made up of nut-like stones aligned with the heavens.

The wreckage of a tragic plane crash is on display at this museum devoted to a famous Italian conspiracy.

A 19th-century artistocrat's mansion, turned into a library, hidden in a modern library.

The mummified right fist of a 1,000-year-old saint-king sits inside an ornate golden reliquary.

Festival of Perpetual Life and Rebirth.