This army of concretions is an unexplained geological phenomenon unlike anything else in the world.

The world's most famous cheese caves.

A remote hilltop covered in giant monoliths haunts the Brittany countryside.

A sublime medieval path adorns the marble floor of one of the most beautiful Gothic cathedrals in France.

A 2017 crowdfunding campaign saved this historic castle from being destroyed.

A museum dedicated to linguistics, from how babies learn to talk to endangered and extinct languages.

This emotive sculpture was originally created for the 1878 World's Fair.

To the famous surrealist artist, liberty required two torches held high.

The mummified heart of Louis XVII, the lost dauphin of the French Revolution.

French commune at the heart of conspiracies.

Despite centuries of architectural innovation, this French castle is being built like it's the 13th century.

Bordered by forest on three sides and the ocean on the other, the Great Dune of Pilat is the highest sand dune in Europe.

An atmospheric, medieval-themed book store hides in a 13th-century underground space.

Series of underground houses inhabited continuously for centuries.

Jean Tinguely's bizarre monster sculpture is hidden deep in a forest.

An ancient ossuary in Rouen.

This lesser-known Frank Gehry building houses a treasure trove of cinema history.

Figures of unknown origin carved into the surfaces of underground caves.

Underneath a chalk hill in France lies what Hitler hoped would be the underground launching base for a devastating new weapon.

Tens of thousands of ancient rock carvings hidden in the heart of a French national park.

One of the world's most complex timepieces.

Lyon's "Wall of the Silk Weavers" is one of the largest murals in Europe.

The castle was reconstructed to fit Kaiser Wilhelm II's romanticized vision of the Middle Ages.

A massive, secret marina for the Nazis' most formidable weapon in the Atlantic.