There was a top secret plan during World War II to seal a group of soldiers inside the rock.

Peek into a cave of giant, glimmering crystals.

An enchanting landscape of ancient sandstone structures eroded into otherworldly shapes.

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

Historic medieval fortified city in southwest France.

Bordered by forest on three sides and the ocean on the other, the Great Dune of Pilat is the highest sand dune in Europe.

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

A spitting ode to a German serial killer.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

You can spot this teeny tiny stained-glass window from the Bonifacius bridge.

Each time a baby is born in Ghent, these streetlights flash in silent celebration.

A massive base for the Nazis' most formidable weapon in the Atlantic.

Wall after wall of this French seaside neighborhood is intricately decorated with seashells and corals.

This submersible road connecting a French island to the mainland is lined with safety towers for when the tide strands travelers.