The ruins of a medieval castle that once belonged to one of the most powerful families in the Netherlands.

This centuries-old hotel hides a network of secret cellars and passages once used by smugglers.

San Gennaro, the patron saint of Naples, greets pedestrians between these narrow city streets.

From toys to kettles to scientific instruments, this German museum celebrates the beauty of 20th century design.

Art and a pun, all in one.

This water-tower-turned-high-end-apartment building was once the site of an early Nazi concentration camp.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

A traditional U-Bahn station in Berlin gets a string of rather untraditional benches.

A surreal museum of extraordinary industrial objects.

A cathedral resurrected from the ashes of one of Europe's greatest urban fires.

For the holidays, the tallest broadcasting tower in the Netherlands turns into one of the world's tallest Christmas trees.

This disused VLF radio station is no longer in service but the surrounding town still bears its name.

This massive steel pyramid can be entered by a set of jagged steps that let visitors stand in its heart.

Chefs from Tibet's Kham region offer steaming meat pies and noodle soups in this nook behind a jewelry store.

The celebrated eyesore created by starry-eyed sweethearts.

The legendary giant's severed hand sits on Antwerp's popular shopping street.

The defensive tower was built centuries ago to warn locals of Berber pirate attacks.

The oldest volcanology research center in the world.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

This amazingly well-preserved villa just outside Pompeii boasts rare examples of ancient Roman paintings.

The walls and streets of the ancient city are peppered with penises.

Ancient snack bar of the Roman Empire re-opened.

Erotic art covers the walls of the largest ancient pleasure palace.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.