An eclectic art form practiced by untrained masters is celebrated at this museum in the heart of Zagreb's old Upper Town.

A tower marking the spot where Yugoslavia began its resistance against the invading Nazis stands neglected, but not quite forgotten.

Croatia's towering concrete blossom grows from the site of a World War II concentration camp.

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

Humble beginnings for one of the world's most famous scientists.

A wonderfully strange collection of 500+ stuffed frogs doing people things.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

A musical instrument played by the sea.

"Holy Wisdom" overlooks the city that became its namesake.

This once-grandiose behemoth of a monument from the socialist era now sits quiet and closed up.

A spectacular Bulgarian cave resembling a devil's head with a waterfall rushing down its throat.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

A former bank seized as a sniper vantage point during the Bosnian War is now a secret graffiti art gallery.

This abandoned Olympic skiing facility still bears the scars of the Siege of Sarajevo.

The place where World War I began.

This top-secret nuclear bunker hidden in a Bosnian mountain has been converted to a modern art exhibition space.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

A war-torn Olympic relic is being overtaken by graffiti and nature.

There's a mini version of Iguazu Falls hidden in the Balkans, and it's got a rope swing.

These warring psychedelic crags commemorate an unsuccessful military operation.

Yugoslavia's biggest underground airport lies in ruins.

The vast chamber inside this abandoned cooling tower looks like something out of a sci-fi dystopia.