In this brilliant blue spring in Germany, legend has it that a sad mermaid learned to finally laugh.

A former ironworks that was the first UNESCO industrial site.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

Old batteries and frog skeletons reside in this lakeside monument to Alessandro Volta.

Pyramid shaped monument with a tall tale attached.

An old slaughterhouse now holds the largest collection of pig artifacts.

This subterranean shrine beneath a bike rental store celebrates the iconic Italian scooter.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The celebrated eyesore created by starry-eyed sweethearts.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

A historic house left in "dramatic still life."

Erotic art covers the walls of the largest ancient pleasure palace.

The walls and streets of the ancient city are peppered with penises.

Ancient snack bar of the Roman Empire re-opened.

A hermit's tiny cell built into the cliffside that saved him in South Pembrokeshire.

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

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

According to the Guanches, the aboriginal people of the Canary Islands, the king of evil lives inside this volcano.

This picturesque horseshoe weir was first built in the 1600s to prevent flooding in the town of Bath.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

The largest greenhouse in the world is home to over one million types of plants.

The twists and turns of this serpentine maze are over 170 years old.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.