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

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

Skeletons, medical artifacts, and other obscure and precious treasures all displayed in a wooden pharmacist's cabinet.

A modern-day Lascaux cave underneath Paris.

The curious underground history of keeping Paris clean.

Original cabaret handbills, posters, and feline artwork are a purrfect highlight of the Museum of Montmartre.

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

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.

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

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

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

Abandoned railway line circling the city of Paris.

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

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

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

These enlarged egg sculptures represent the native birds of eastern Iceland.

A museum dedicated to the tragedy of Bloody Sunday.

Celebrated in poem, this tiny hidden cemetery has a big and grisly history.

A Victorian marvel of engineering is now a 21st-century tourist attraction.

The "Black Arch" guards the entrance to the picturesque Glens of Antrim.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

This 18th-century fort surrounded by a moat was used to store gun powder and ammunition, and now sits in the middle of a large part in Dublin.

This former World War II torpedo testing location is now an important nesting site for migratory birds.

This mysterious Bronze Age standing stone has become a place where couples profess their love.