French commune at the heart of conspiracies.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

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

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

Cold war icon and onetime "hole" in the iron curtain.

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

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

Send a postcard while vacationing with Satan.

A monument celebrating the idea of reaching inaccessible places.

"We Seceded Where Others Failed."

Japanese gardens dedicated to the Japanese farmer that refused to throw in the trowel.

A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

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

Former villa and estate of James Deering developed to preserve native tropical forests.

A UFO-shaped event building originally intended to be a science museum showcasing the future.

Even France's favorite aquatic son Jacques Cousteau, couldn't get to the bottom of it.

A pilgrimage site where people ask Saint Dymphna to watch over those who are not of sound mind.

A church of bones, decorated with 40,000 human skeletons.

A seven-century-old jail tells a not-so-pleasant history of crime and punishment.

A little sculpture with a large wardrobe.

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.

Colorful and chaotic stacked hotel in North Holland.