Catacombs turned marketplace.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

This secluded walkway overlooks a magnificently wild London green space.

A massive, secret marina for the Nazis' most formidable weapon in the Atlantic.

This demon atop the Notre-Dame de Paris looks utterly bored.

An all-American grocery store in Paris sells U.S. "cuisine" like Pop-Tarts and Heinz ketchup to homesick ex-pats.

During the summer months, giant teddy bears take over Paris near Les Gobelins metro station.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

The video game-themed street art first popped up in the French city.

This recessed garden protects thousands of mountain plants by creating its own microclimates.

A mud statue stands in the dark tunnels, seeming to hold up the weight of the city above.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

The narrowest street in Paris.

A French artist's vague warning hangs over Belleville.

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

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

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

The former home of France's controversial pop maestro is almost completely covered in ever-changing tributes and graffiti.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

Pitié-Salpêtrière was the dumping grounds for women who received the dreaded diagnosis of "hysterical."

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

This Parisian fountain is a little bit fantasy and a little bit nightclub.