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

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

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

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

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

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

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

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

Indents in the pavement are all that remain from a grisly death machine in Paris.

Abandoned railway line circling the city of Paris.

A museum of magic with a Sadist past.

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

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.

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