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.

The recovered bones of martyrs slaughtered during The Terror are on display in this church crypt.

The headless bodies of more than 1,300 guillotined victims of the Reign of Terror are buried here in mass graves.

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

This little-known relic crypt holds stolen parts of a Roman Empress.

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

Two awe-inspiring globes from the reign of the Sun King hang from the ceiling of France's national library.

A Parisian exterminator's shop whose storefront displays stuffed rats hanging from traps.

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

The history of radiation is on safe display at the foot of a radiation science laboratory.

Statue of death tucked in the University of Medicine courtyard.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

A surrealist timepiece by the artist of melting clocks.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

A mechanized clock where a man fights off a dragon, crab, and rooster.

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

A museum of carnival attractions where you are invited to ride the rides.

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 oldest stone house in Paris was built by its most famous alchemist.

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

Notorious artist squat renovated into legal studios.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

The canine-themed book collection claims to be Europe's largest dog library.