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

The haunting ruins of a military fortress turned astronomical observatory sit on a Sarajevo mountaintop.

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

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

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

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

This surreal memorial/cemetery is a necropolis of crumbling stonework and puzzle-shaped headstones.

The sad remains of a monument to martial arts legend and movie star Bruce Lee—in the middle of Balkans.

An apparition of Virgin Mary in Herzegovina.

This abandoned airplane hanger is said to have once been a top secret launch facility.

A full figure 4th century incorruptible saint lies in a glass coffin in Croatia.

These warring psychedelic crags commemorate an unsuccessful military operation.

A sinuous path among steep cliffs creates a stunning sight in southwestern Serbia.

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.

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

A curious cave church carved into the face of a cliff.

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

This massive subterranean fissure is known as the "underground Grand Canyon."

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.

This abandoned Slovenian military barracks has become a punky-political art squat.

The remains of the last Bosnian fortress to fall to the Ottomans are still standing.

This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.