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

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

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

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

An icy lake tucked among jaw-dropping alpine panoramas.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

A subterranean shelter remains intact under a busy Paris railway station.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This Parisian café sticks almost exclusively to an ethos of reuse.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

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

Notorious artist squat renovated into legal studios.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

Abandoned railway line circling the city of Paris.

France's most famous cemetery, with some of its most curious tombs.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

A rare octagonal brick beacon on an isolated island in the Baltic.

The tallest lighthouse in the Nordic countries was also the site of a bloody World War II battle.

This abandoned villa of makeshift buildings was once the home of dancer Elis Sinistö.

Hidden deep in a forest is this geological wonder carved by glaciers.

This lake-bound geographical marker sits at the point where three European countries intersect.

This irregularly shaped sea fortress has defended not one but three different sovereign states.

Despite finally receiving electricity in 1970, this tiny town is now deserted.