Explore this medieval cathedral by trying to spot all the malevolent monsters hiding in its beautifully colored windows.

There has been an astronomical clock on this spot since the 14th century.

A statue in the heart of Edinburgh honors a bear that served in the Polish military during World War II.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

The fountain marks the area where hundreds of accused witches were burned at the stake.

A six-ton wedding present for the King of the Scots.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

The final resting place of soldiers' loyal canine companions.

This contentious squat has stood through fire, violence, and government intervention as a hotbed of leftist protest.

Hamburgers are intensely proud of their tunnel beneath the river.

Remnants of an exploded schooner and wrecked submarines form a breakwater.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

One of the longest wooden benches in the world snakes around Geneva's Treille Promenade.

A beautiful maze marks where three countries meet.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

Visit the ancient, mysterious Roman catacombs ... in the Netherlands.

A distinctive former power plant turned university lecture hall looks like it could make you breakfast.

Hiding the longest subterranean river known in the world.

This "floating railway" is one of the world's oldest monorail systems.

The small alleys in Lübeck's Old Town are a result of medieval urban sprawl.

A tilted half-timbered house from 1672 is built into a salvaged segment of a medieval wall.

There is a strange little carving of a person seemingly crushed by a pillar behind the remains of St. Thomas Aquinas.

Legend has it this 11th-century castle was paid a visit from the devil.

This "flat geyser" bubbles up out of the ground periodically like a disappearing river.