Hidden away in a modern library are the remains of one of the 18th century's most celebrated wunderkammers.

Do these monsters look familiar? The gargoyles on this church are all from pop culture.

The largest underground church in Europe.

The only remaining collection of flayed figures made by French "madman" Honoré Fragonard.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

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

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

Hundreds of hidden passageways weave through the old quarters of Lyon.

Science fiction's grandfather has a fittingly marvelous tomb.

Ancient paintings known as the "Sistine Chapel of Cave Art."

One of the greatest maze designer’s greatest mazes.

A grotto-like lodge decorated with gilded mosaics, rocks and a noisy waterfall was the setting for the most sumptuous pleasure house of 1900s Europe.

Paris' fabled purveyor of exotic taxidermy and natural history curios.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

"In the Dark" Restaurant in Paris offers dinner in complete darkness.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

A museum of magic with a Sadist past.

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

Every year, the town of Menton, France, turns lemons and oranges into giant sculptures depicting windmills, dragons, and more.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

Countless grotesque faces stare out from this eerie Prague art wall.