An early 20th-century sanatorium, long abandoned and now being reclaimed by nature.

This Belgian palace was long the domain of priests and aristocrats but is now being turned into an art commune.

Hiding the longest subterranean river known in the world.

Be it nature, art, or abandoned military architecture this eclectic German "museum" has you covered.

This massive collection of taxidermy is full of specimens collected by missionaries during their international travels.

Museum covers every step of the chocolate-making process, from cultivation to the finished product.

Incredible labyrinth of man made caves.

A luxury hotel housed in a former 15th century Gothic church.

This centuries-old gothic monster has been converted into a sprawling, glossy bookstore.

A beautiful maze marks where three countries meet.

This bakery and museum offers tours of the tastes and mythology of Aachen's signature spice biscuit—just don't ask for the recipe.

A distinctive former power plant turned university lecture hall looks like it could make you breakfast.

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

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

Architect Le Corbusier built his friend a cubist house to match his impressive collection of cubist art.

In this Parisian garden's grotesque former life as a zoo it fed exotic animals to the bourgeois and put humans on exhibit.

BDSM, 1930s Style.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

The recovered bones of martyrs slaughtered during The Terror are on display in this church crypt.

This Paris art space celebrates the creativity and ingenuity that springs from abject poverty, especially in Africa.

An iconic and eccentric bar for "Manouche" Jazz music keeps expanding its space—and its influence.

An immersive projection art installation uses sound, scale, and light to take visitors inside classic works of art.

Where the high court feasted, frolicked, and high courtesans put their royal lovers' diamonds to the test.

This frog-themed restaurant was frequented by Picasso, Saint-Exupéry, and more.