The personal library of the founder of modern neurology is open to visitors.

An unusual number plate signifies the building's saucy past.

One of the oldest masonic museums in Paris.

A museum which takes visitors to the côté obscure of Paris.

The Sun King's military models, saved from the Louvre.

Architect Le Corbusier built his friend a cubist house to match his impressive collection of cubist art.

This innocuous-seeming building is actually the remnant of a major wartime brothel.

BDSM, 1930s Style.

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

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

Saintly bones pressed into a wax effigy of a Catholic superstar.

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 floorboard scrawling of a tragic madman is on public display outside a Paris hospital, much to the dismay of its opponents.

A modern-day Lascaux cave underneath Paris.

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

Museum on French naval history, with magnificent figureheads, a historic diving suit, and a boat used by Napoleon.

This Paris art space celebrates the creativity and ingenuity that springs from abject poverty, especially in Africa.

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

Got apples?

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

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

Noirish green neon marks the location of one of the oldest private detective agencies in France.

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

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