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.

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.

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

A French library that makes sure its love of books is writ large... giant in fact.

Perhaps the most beautiful of preserved saints, with a little help from Paris.

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

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

An ancient ossuary in Rouen.

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

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

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

This submersible road connecting a French island to the mainland is lined with safety towers for when the tide strands travelers.

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.

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

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

One of the world's most complex timepieces.

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

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

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

Bits of architecture from a town destroyed in World War I now decorate this hotel garden.

The deserted pirate-themed restaurant still entices explorers.