The abandoned ruins of a beautiful medieval castle just outside Barcelona.

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

Since the 1700s, this old barrel has acted as a post box that relies on the kindness of travelers.

A rocky sea serpent hides caves, blowholes, and a spectacular natural bridge.

The oldest continual pilgrimage site in Britain was supposedly created by a gruesome beheading.

A hermit's tiny cell built into the cliffside that saved him in South Pembrokeshire.

A museum dedicated to the Spanish occult in a town that was terrorized by the Inquisition.

This mysterious underground cave in Shropshire dates back to the 18th or 19th century.

This sword isn't waiting for a king to pull it out. It was placed there by a saint.

The heart of a Scottish legend had a centuries-long journey before reaching its final resting place.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

The studio of Catalonia's most famous theatrical designer remains exactly as he left it.

The beautiful baroque library of the Hapsburg empire.

Where once there was a train station bathroom, there is now this German burger joint.

A surreal museum of extraordinary industrial objects.

Berlin's oldest surviving academic architecture hosted decades of animal dissections.

Home to 10,000 medical specimens including the remains of Rudolf Virchow's extensive collection of pathological specimens.

An eerie, derelict amusement park in Berlin.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

The most visited, and possibly most controversial, museum in Germany.

The loneliest island in New York.

Run by a eugenics advocate, this aging institution conducted secret radiation experiments sponsored by Quaker Oats.

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

Historic psychiatric asylum and most-filmed location in the Great White North.