The sunken structure looks like the victim of a catastrophic flood.

An ancient monastery, a locked room, and a mysterious book heist.

A chapel on a volcanic core, marking the end of a successful journey.

A tiled, multi-level garden of survival in Lyon.

A self-built mosaic house and sculpture park.

This medieval tower is all that remains of the castle where Joan of Arc was held before being burned at the stake.

A mud statue stands in the dark tunnels, seeming to hold up the weight of the city above.

Since ancient times these picturesque springs have been providing bathers with healing waters.

An enchanting work of outsider art, full of whimsical sculptures and carvings.

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

Two small chapels housed inside an ancient tree.

Beautiful carved tunnels.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

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

These quaint French houses dangle precariously over a precipice.

The fantastic architectural models of a French traveler.

Ivy-covered Medieval tunnels cut through this charming town in France's Loire Valley.

A medieval military street hidden beneath a charming French fishing village.

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

Monsters and miniatures are held in equal esteem at this wondrous museum.

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

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

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

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