Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

A limestone grotto where daylight filters in from below and turns the water a beautiful turquoise. Also home to a small underwater nativity scene.

Amalfi's pre-industrial history is slowly being engulfed by the lush vegetation of the Ferriere Valley.

A medieval bridge stretches over a sulfur-rich river that leads to year-round natural hot springs.

This 16th-century house tells the city's history through old artifacts and quirky tales.

The largest Roman amphitheater in the Balkans once held over 20,000 people, but managed to lay hidden for hundreds of years.

Bronzes and busts that once stood in the city's main squares are now relegated to a small hidden courtyard.

Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

What happens when you cross a mayor and a painter?

A naturally beautiful, seemingly bottomless deep blue spring.

An American ghost town hides along a side street in Scotland's capital.

Possibly the world's smallest museum is home to one exhibit that sheds light on the capital city's dark criminal history.

These steps offer a breathtaking view of one of Europe's most besieged fortresses.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

The Belgian royal family's private depot now stands abandoned and forgotten alongside the tracks.

Nature is slowly overtaking this disused cemetery on the outskirts of Brussels.

This recently restored crypt was once plagued by liquefying coffins and exploding caskets.

Theme park featuring miniature replicas of European monuments.

A rare, flower-shaped example of Brutalist architecture in Switzerland.

An early Portuguese serial killer's head is alarmingly well preserved in a jar at the University of Lisbon.

A garden in Lisbon filled with giant porcelain creatures.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

The curios of pharmacist and collector Henry Wellcome.

Legend says these stone structures are where the doomed citizens of a vanished village sent themselves to die.