Visitors dating back to the 1600s carved their marks in the stones of the iconic tower.

Today this former Nazi concentration camp stands as a poignant memorial to the victims of fascism, and a warning from history.

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

The castle was reconstructed to fit Kaiser Wilhelm II's romanticized vision of the Middle Ages.

Wander among free-roaming storks at the sanctuary that helped save them from local extinction.

A copy of the Statue of Liberty greets visitors to the birthplace of Auguste Bartholdi.

An image of the legendary saint stands in the shadow of a cathedral she liberated.

A swath of France so devastated by war it is still forbidden to go there.

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

A 12th-century castle featuring a sensory path where partially-sighted visitors can experience regional history through touch and sound.

This magenta statue commemorates the legendary marriage between a mermaid and the city's founder.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Statues of a fire-breather, a clown, and a whole performing troupe celebrate Luxembourg's creative side.

Some believe that the artist behind this whimsical statue inserted his own likeness as a way to discreetly flip the bird.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

In the heart of Luxembourg's "little Switzerland" weaves a breathtaking natural sandstone canyon with a mythological past.

The remains of the medieval wall that once surrounded Paris with ties to the construction of the Louvre.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

After immigrating to Paris in the 1970s, two brothers from Laos built a grocery store empire.

Pitié-Salpêtrière was the dumping grounds for women who received the dreaded diagnosis of "hysterical."

This lesser-known Frank Gehry building houses a treasure trove of cinema history.

A museum of carnival attractions where you are invited to ride the rides.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

The first green space constructed on an elevated viaduct.