An ancient monastery, a locked room, and a mysterious book heist.

A well-preserved medieval village nested on a rocky outcrop and surrounded by a network of cliffs, natural bridges and canyons.

Beautiful carved tunnels.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

Two small chapels housed inside an ancient tree.

A beautiful and classically designed villa, with an hourly infestation of monsters.

The famous winding walk at Chartres is surrounded in mystery and myth.

A Gothic cathedral created from volcanic rocks.

The mental institution where Van Gogh created some of his most famous work now allows guests to walk in the artist's footsteps.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

The largest underground church in Europe.

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

Do these monsters look familiar? The gargoyles on this church are all from pop culture.

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

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

Ancient paintings known as the "Sistine Chapel of Cave Art."

The curious underground history of keeping Paris clean.

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

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

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

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

This museum houses an imposing skeleton army comprised of creatures great and small.

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