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

A modern-day Lascaux cave underneath Paris.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

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

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.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

A haunting collection of the vanished and disappearing natural world.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

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

Paris' fabled purveyor of exotic taxidermy and natural history curios.

Statue of death tucked in the University of Medicine courtyard.

Weird wax anatomical models reside here, as do other anatomical specimens.

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

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

The largest medical and anatomical collection in France lies hidden from the public.

Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

This museum houses an imposing skeleton army comprised of creatures great and small.

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

A surrealist timepiece by the artist of melting clocks.

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

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

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.