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

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.

A king's bloodstained shirt is among the gruesome collection of artifacts displayed below Stockholm's Royal Palace.

A medieval village, with red wooden cottages around a stone church, stands as a well-preserved example of a settlement type that was once common in northern Sweden.

If you visit Santa's village, you can get your passport stamped to show you crossed into the Arctic Circle.

World's strongest whirlpool.

This roadside attraction looks like a flying saucer parked atop the tundra.

The world's first and only escalator for lazy bicycles and their daunted riders.

A serpentine highway twists and turns over the treacherous Norwegian Sea.

Elaborate tile work in this railway station tells the story of Portugal.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

The world's largest wooden structure.

Spain's largest bullring offers a unique glimpse at architecture and history.

This former charity hospital for elderly clergy houses some of Seville’s most treasured paintings.

A museum dedicated to the centuries-old cave dwellings that housed marginalized communities on the outskirts of the former capital of Muslim Spain.

A Spanish town built into the cliffs.

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

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Single runway interrupted by a busy road that cuts across its middle.

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

Red, white, and blue painted steps along with a Union Jack celebrate the outcome of Gibraltar's 1967 referendum.

Founded as a refugee camp, now a popular tourist spot.

The courtyard of this small Marinid madrasa is a dazzling example of intricate Islamic architecture.

Traditional 11th-century outdoor tannery.