Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

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

The cave of a 12th-century hermit is still visited and venerated today.

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

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

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

The only microgravity tower in Europe can produce nine seconds of weightlessness.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

The mark of the Devil's horns on a marble column in Milan.

Just across from the "Last Supper" painting is the famous painter's vineyard, a gift received for creating the masterpiece.

These quaint French houses dangle precariously over a precipice.

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

A chapel on a volcanic core, marking the end of a successful journey.

This crack in France's seaside cliffs once hid a sinister secret.

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

A 2017 crowdfunding campaign saved this historic castle from being destroyed.

The great Italian Renaissance painter was laid to rest here in the Chapel of Saint-Hubert.

The opulent home that inspired Tintin's Marlinspike Hall and the adventures within.

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

César Baldaccini's iconic sculpture of a 40-foot thumb stands tall in La Défense.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

A mud statue stands in the dark tunnels, seeming to hold up the weight of the city above.

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