Abandoned railway line circling the city of Paris.

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

Former hunting lodge of a duke who was an avid collector of impressionist works.

An odd museum dedicated to French fakes.

This Parisian café sticks almost exclusively to an ethos of reuse.

A modern-day Lascaux cave underneath Paris.

The curious underground history of keeping Paris clean.

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

Egyptian Revival movie palace abandoned for decades and restored in 2013.

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

A grotto-like lodge decorated with gilded mosaics, rocks and a noisy waterfall was the setting for the most sumptuous pleasure house of 1900s Europe.

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

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

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

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

Where the high court feasted, frolicked, and high courtesans put their royal lovers' diamonds to the test.

France's national museum of scientific and industrial instruments.

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

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

A curious collection of locks and keys.

A surrealist timepiece by the artist of melting clocks.

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

An all-American grocery store in Paris sells U.S. "cuisine" like Pop-Tarts and Heinz ketchup to homesick ex-pats.

A museum of magic with a Sadist past.