One woman's decades-long obsession with the "La Fée Verte."

The fantastic architectural models of a French traveler.

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.

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

Two small chapels housed inside an ancient tree.

The famous winding walk at Chartres is surrounded in mystery and myth.

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

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

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

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

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

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

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

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The oldest stone house in Paris was built by its most famous alchemist.

Abandoned railway line circling the city of Paris.

Notorious artist squat renovated into legal studios.

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.

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

This 600-year-old home seems to defy physics.

These bronze pamphlets remember a remarkable group of Germans who fearlessly opposed the Nazis in the very center of their power.

Among the ostentatious rococo ornamentation of this church, an image of death cuts the life-thread.