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

One of the greatest maze designer’s greatest mazes.

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

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

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

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

Two small chapels housed inside an ancient tree.

The largest underground church in Europe.

A Gothic cathedral created from volcanic rocks.

For hundreds of years, automatons moving to metallic music have been marking the passage of time.

Sleep in a climate-controlled plastic bubble for the night.

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

The world's tallest bridge is also possibly the most elegant.

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

A self-built mosaic house and sculpture park.

Nicknamed the "Museum of Horrors," this French anatomical collection has been fascinating visitors for over a century.

This modern museum of Mediterranean culture is surrounded by a surreal concrete honeycomb.

Miles of man-made caves and tunnels are currently used for cultivating mushrooms.

Artist and musician Will Menter creates musical sculptures.

One of the largest ochre quarries in the world, hidden in a limestone landscape.

Thousands of flamingos and other bird species flourish in these Camargue wetlands.

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

This French anatomy museum greets guests with a skinless man, mid-shovel.