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

A large collection of ancient runestones decorates this university courtyard.

On a winding Vienna side street, one museum has turned their windows into a monument to history’s peace-minded heroes.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

During the Soviet era, the spire of this longstanding church was used as a radio transmission tower.

The geographical center of Budapest is marked with a 10-foot-tall stylized zero.

A relic of World War I that now exist as a piece of public art.

A triumphant marble and bronze fountain depicting a 15th-century Hungarian king and his hunting party.

Legend says this rock spire is the finger of a witch who wanted to throw the Faroe Islands towards Iceland.

This remote island village was in danger of depopulating completely until a tunnel was built to connect it to the rest of the world .

The main feature of these gardens is a rarity in the northernmost part of Scotland: trees.

Visitors dating back to the 1600s carved their marks in the stones of the iconic tower.

A Trabant car, a kangaroo statue, and a plethora of plants take over this abandoned-factory-turned-bar.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

Baroque celebration of the end of the Great Plague of Vienna.

Launched by Napoleon's soldiers more than 200 years ago, a cannonball remains embedded in the tower wall.

Also known as the Blue Church, the building was consecrated to the daughter of Andrew II.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

Exquisite carvings of leaves, Green Men, and the occasional dragon adorn a medieval chapter house.

This English medieval castle is where King John died of dysentery.

In the U.K., a historic workhouse shines a light on the early, harsh treatment of the poor.

The ancestral home of beloved English poet Lord Byron has a bizarre history.