This massive underground salt mine now holds a sci-fi theme park in its depths.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

A tiny church on a man-made island in the Adriatic.

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

The ceiling of this cavern is dripping with multicolored marble stalactites.

Two distorted Romanesque columns hold aloft a mine cart in honor of laborers who died during WWII.

A 11-foot former president stands on a Kosovo street that also bears his name.

A futuristic, brutalist masterpiece that is also strangely prison-like.

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

The now-overgrown beach resort was once frequented by Yugoslav military elite.

This former estate of a fascist leader is now a burnt out ruin leading to a system of secret tunnels.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

Gargoyle head that brings good luck.

Yugoslavia's biggest underground airport lies in ruins.

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

A museum dedicated to secret surveillance.

What happens when you cross a mayor and a painter?

Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.

The romantic botanic tunnel feels like a well-kept secret.