Green labyrinth formed by a karstic maze hidden in a preserved oak forest.

This otherworldly French waterfall looks like its waters have turned to stone.

Natural mummies hidden in the crypt of a medieval French church.

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

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

Perfume museum and library.

This narrow path was cut right into a French mountainside to feed the country's early naval expansion.

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

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

A French valley with forests so lush it was nicknamed "the Small Amazonia of the Pyrenees."

This futuristic observatory at the top of the Pyrénées offers unrivaled views.

An isolated 17th-century chapel on a remarkable site once dedicated to Celtic sun worship.

A quaint medieval millhouse hovers surprisingly above the waters of the Seine.

The construction of a tram line unveiled hidden remnants of the old medieval city.

These crumbling Nazi artillery bunkers are now fair game for massive graffiti projects.

Located in the house where Gustave Flaubert was born, this odd museum has more to do with medical grotesquery than the Western novel.

A unique underground structure dating back to the 1st century BC.

A centuries-old complex of hand-dug stone chambers has sheltered locals in times of trouble.

A colossal sculptural lion built by the same man who designed the Statue of Liberty.

The 16th-century church was kept in its ruined state as a reminder of the casualties of World War I.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

This crumbling, graffiti-covered mansion sits tantalizingly within reach of the proletariat who frequent a public park.

One of the world's most complex timepieces.

The Church of the Annunciation was carved into the face of a cliff, just like the rest of the town of Haute-Isle.