A historic observatory precariously perched at the "Top of Europe."

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

This medieval cathedral houses stained-glass windows featuring saints and pretzels.

A stonemason's hilarious revenge came in the form of this peculiarly positioned gargoyle.

These paved rills bring freshwater into Altstadt and could spell wedding bells for whoever stumbles into the waters.

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

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

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

A charming little museum founded by the designer of the Statue of Liberty.

This unusual piece of Renaissance art depicting the bodily horror of crucifixion and skin disease may have been inspired by fungus-induced hallucinations.

The birthplace of the builder of the Statue of Liberty is now a museum dedicated to his work.

This famous archeological mystery may be an ancient example of movable type.

Swarms of dainty flying insects swarm into the Petaloudes Valley to get busy.

A charming beach town in Turkey captures all the colors of the rainbow.

Ancient ruins hidden underneath a modern luxury hotel.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

This museum housed in a former brothel explores the past and present of sex work in Amsterdam.

This bird-loving brewery is situated in an old municipal bathhouse, nestled beside a 300-year-old windmill.

A public urinal so pretty, it was declared a national monument.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

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

Hamburgers are intensely proud of their tunnel beneath the river.

After it was swallowed by a Georgian mansion, this medieval castle remained forgotten for centuries.