This secret cemetery where no flag is allowed to fly holds the bodies of American soldiers convicted of heinous crimes during WWII.

An odd museum dedicated to French fakes.

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

A modern-day Lascaux cave underneath Paris.

The artist and his brother are buried in a landscape straight out of a van Gogh painting.

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

If they push on just the right spot, even the weakest person can move this titanic boulder.

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

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

The world's largest reflecting pool is just two centimeters deep.

BDSM, 1930s Style.

An icy lake tucked among jaw-dropping alpine panoramas.

A public park off the beaten path with a beautiful waterfall and 13th century Cistercian abbey.

The floorboard scrawling of a tragic madman is on public display outside a Paris hospital, much to the dismay of its opponents.

Museum in a swimming pool where the water still flows.

This stunning natural double arch, the largest in the Alps, went undiscovered until 2005.

A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

An all-American grocery store in Paris sells U.S. "cuisine" like Pop-Tarts and Heinz ketchup to homesick ex-pats.

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

This natural French spring has been turned into a magical grotto by Roman and medieval constructions.

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

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

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