A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

Fossils, railroads, and waterfalls!

Scattered throughout London are ancient remnants of the city's former bounding wall.

Vast stretch of tide-pools with a unique Moroccan charm.

It houses the remains of a 17th-century version of the Titanic.

Sweden's "good old days" painstakingly re-created in a model village.

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

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

Catacombs turned marketplace.

Gigantic Romanian salt mines used to heal respiratory conditions.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

The most visited, and possibly most controversial, museum in Germany.

Cold war icon and onetime "hole" in the iron curtain.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

Macabre astrological automaton clock dating to the late 1400s.

Oriental bazaar in the heart of Sarajevo.

Bridge that died in war and was resurected.

Controversial site of what could be Europe's first pyramid.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

A musical instrument played by the sea.

A miniature train-ride through Slovenia's largest cave system.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

The "dragon babies" of southeastern Europe.

This one-time health resort was used by aristocrats around the world.