A massive cave once a secret military base is now home to thousands of bats.

Massive, unfinished broadcasting station stands as a monument to the fall of communism.

Founded in the 4th-century, the town of Pernik plays host to the Surva Carnival⁠—a magnificent display of masked Kukeri dancers.

An abandoned resort in North Macedonia is a relic from the Communist Party of Yugoslavia.

Depending on the region's rainfall, this church may be partially submerged.

Now abandoned, the world's first torpedo factory is crumbling into the sea.

The only gulag ever to exist in socialist Yugoslavia.

When Croatia became independent of Yugoslavia, the splintering governments left behind these concrete tunnels.

Croatia's "hairy stone" fortress is one of the most well preserved Istrian castles.

This Croatian fairytale castle is slowly falling apart thanks to years of neglect.

This huge metal monument is slowly being stripped to its concrete skeleton.

Legend has it fairies gathered at the site of this medieval castle.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

Scars of this building's past life as a violent prison still cover its walls.

This 13th-century monastery chiseled into the side of a mountain is equipped with a bridge that can be lifted to protect against raids.

The hermits of Karoulia protect their asocial lifestyles by living on the vertical face of a treacherous precipice.

This World War I fortress is the perfect place to catch a Montenegrin sunset.

The ruins of a military-industrial complex now host concerts and more.

This apartment is a true time capsule of local life in Bulgaria during the Soviet regime.

The second-largest Jewish temple in Bulgaria was deserted after World War II, seized by the communist government and then abandoned again.