The world's largest reflecting pool is just two centimeters deep.

A self-built mosaic house and sculpture park.

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

A mosaic-tiled house built by graveyard sweeper Raymond Isidore.

This stunning French estate was so lavish that it landed its original owner in jail for the rest of his life.

A well-preserved medieval village nested on a rocky outcrop and surrounded by a network of cliffs, natural bridges and canyons.

Museum in a swimming pool where the water still flows.

The headless bodies of more than 1,300 guillotined victims of the Reign of Terror are buried here in mass graves.

Museum on French naval history, with magnificent figureheads, a historic diving suit, and a boat used by Napoleon.

This stunning natural double arch, the largest in the Alps, went undiscovered until 2005.

This salt marsh in Southern France is as pink as the flamingos that inhabit it.

This professional clown's home is an outsider art wonderland.

Beautiful carved tunnels.

Avant garde house of Pierre Cardin on the Cote d’Azur.

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

An aluminum skeleton brings Chinese mythology to the French shore.

A Gothic cathedral created from volcanic rocks.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

The largest underground church in Europe.

Do these monsters look familiar? The gargoyles on this church are all from pop culture.

Hidden away in a modern library are the remains of one of the 18th century's most celebrated wunderkammers.

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

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

The only remaining collection of flayed figures made by French "madman" Honoré Fragonard.