A secret hotel room can be found inside this clocktower in the oldest city in Austria.

German and American troops joined forces to defend this fortress during the strangest battle of World War II.

Each year melting snow turns these Austrian hiking trails into scuba zones.

The beautiful, ornate weather station is the most popular geocache in Salzburg.

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

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

The bones of some 7,000 soldiers killed in the historic Battle of Solferino are stored here.

The skulls and bones of thousands of soldiers line the walls of this small Italian chapel.

How did a French journalist’s grave become the sexiest statue in the cemetery?

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

Science fiction's grandfather has a fittingly marvelous tomb.

This recently restored crypt was once plagued by liquefying coffins and exploding caskets.

Huge Russian Orthodox cemetery in danger of being converted into open public space.

Natural mummies hidden in the crypt of a medieval French church.

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

A stunning cemetery famous for its extraordinarily delicate & lifelike mourning sculptures.

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

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

Museum celebrating the ocean, with the largest wunderkammer dedicated to sea exploration.

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

In the heart of Luxembourg's "little Switzerland" weaves a breathtaking natural sandstone canyon with a mythological past.

This imposing memorial contains the remains of Che Guevara — and 29 other guerrillas who died with him in Bolivia.

After the Cuban Revolution, the famous rum company had to leave their swanky headquarters behind.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.