A moody and picturesque riverside ruin overgrown with vegetation.

The mummified heart of Louis XVII, the lost dauphin of the French Revolution.

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

Down a cobblestone alleyway is a museum dedicated to Romanticism, with a secret garden.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

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

The oldest stone house in Paris was built by its most famous alchemist.

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.

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

A counter-culture bookstore like no other hides in plain sight in the streets of Paris.

This banal Parisian entranceway is not what it seems.

Stroll through retro Paris while shopping for old postcards and discarded doll heads.

Bits of architecture from a town destroyed in World War I now decorate this hotel garden.

Hundreds of dwarf beeches create an unusual, haunting forest in the north of France.

The world's oldest Jewish library was founded by Sephardic Jews in 17th century Amsterdam.

The childhood home of Henry Jones Jr. is now an adventure-themed bed and breakfast.

The haunted reputation of these abandoned Colorado train tunnels is probably not helped by the terrifying spiked fence.

One woman's UFO-themed campground, complete with self-built energy vortexes, UFO-themed weddings, and magic bushes.

Wondrous sandstone hoodoos where Native Americans collected clay for pottery, 9,000 years ago.

This Colorado hiking trail provides a small gold mine of abandoned gold mines.

This grand stone tower was dedicated to a famed American humorist almost by coincidence.