It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

Stockholm's deepest subway station is also a stunning ecological wonder.

What looks like a birch tree smushed between two pieces of glass often confounds commuters.

Outside a Viking museum sits a modern-day runestone made by a Swedish runemaster using traditional methods.

The Swedish flag over this small naval fort signals that the nation is at peace.

The discovery of an old wall led to the creation of this fascinating museum about the city in the Middle Ages.

A man has revenged his true love's betrayal through tears and stone genitalia.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

The world's largest model of our planetary system.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

This multi-level, aqueduct-footbridge hybrid is one of the greatest works of the Spanish Renaissance.

These magnificently sculpted tombs represent Spain's own legendary version of "Romeo and Juliet."

A mysterious shape catches the eye in this 16th-century painting.

A model solar system adds a celestial touch to this suburban park.

The floor of this spectacular Baroque sanctuary is covered in memento mori.

The discovery of these rare, ancient artifacts led to the creation of a new museum.

A small town celebrates its cash crop with a giant highway sculpture.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

This once-forgotten oasis in the middle of Lisbon was first created over a century ago quite by accident.

One man's remarkable private collection of art from around the world.

A breathtaking and biodiverse wilderness in the mountain setting of Ernest Hemingway's "For Whom the Bell Tolls."

Disturbing winged beings decorate the walls of this strange abandoned hermitage.

This technological marvel is one of the world's first 3D-printed bridges.