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

This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.

A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

Historic medieval fortified city in southwest France.

A Gothic cathedral created from volcanic rocks.

A charming flea market shop dedicated to retrofuturistic apparati.

The largest underground church in Europe.

Hundreds of hidden passageways weave through the old quarters of Lyon.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

The curious underground history of keeping Paris clean.

Inside a former cabaret, seven floors of erotic art.

Stroll through retro Paris while shopping for old postcards and discarded doll heads.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

Paris' linguistic guide to the international language of, yes, love.

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.

The celebrated eyesore created by starry-eyed sweethearts.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

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

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

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