The world's oldest known salt mine.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

A spherical "micro-nation" in the heart of Vienna.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

The topiary maze at the Habsburg hunting lodge.

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

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

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

A whimsical bridge adorned with decorative dragons.

Sitting beneath an unremarkable residential building is a museum devoted to classic Pinball.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

A statue in Budapest's Liberty Square honors the former U.S. president's efforts to end the Cold War.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

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

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Once the home of a hermetic monk, this cave now houses a small church.

Budapest's Communist-era statues, banished to the suburbs.

This brutalist monument is inscribed with 9921 names of Yugoslav partisans who perished during WWII.

This exclusive resort has completely covered a tiny Balkan island in a 5-star warren of guest rooms.

Former military fort and site of untold horrors during WWII, this island may become the Adriatic's next luxury resort.

A beautiful mountaintop mausoleum devoted to a Montenegrin icon can't seem to make everyone happy.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.