These headstones and a few stone foundations are all that remain of a once-booming mining town.

The oldest and smallest cemetery in Paris is only open to the public twice a year.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

A popular shrine where the Blessed Virgin allegedly appeared in 1830, displaying a holy armchair and two incorruptible remains of Lady Saints.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

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

A subterranean shelter remains intact under a busy Paris railway station.

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

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

Abandoned railway line circling the city of Paris.

Notorious artist squat renovated into legal studios.

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

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

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Passengers are not allowed to set foot outside this station, but you can still enjoy spectacular views of the sea from the platform.

The secret wartime bunker built on the platforms of an abandoned Tube station.

Unchanged for decades, World War II-era bullet holes and nostalgic ghost signs still haunt this desolate train station.

A portrayal of two lamps embraced and in love.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

Tucked away behind the mansions of Mayfair, this picturesque garden is a hidden London treasure with a spooky past.

Planes, helicopters, and a shipwreck are underwater in this former limestone quarry.

This amazing trail among the many waterfalls around Ingleton has been enchanting visitors since 1885.

A shrine to the missionary who first brought Islam to China.