The largest underground church in Europe.

A Gothic cathedral created from volcanic rocks.

This natural French spring has been turned into a magical grotto by Roman and medieval constructions.

The mental institution where Van Gogh created some of his most famous work now allows guests to walk in the artist's footsteps.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

An icy lake tucked among jaw-dropping alpine panoramas.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

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

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

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

These quaint French houses dangle precariously over a precipice.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

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

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

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

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

France's national museum of scientific and industrial instruments.

Abandoned railway line circling the city of Paris.

"In the Dark" Restaurant in Paris offers dinner in complete darkness.

A museum of magic with a Sadist past.

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.