An abandoned train station in Munich constructed for the 1972 Olympic games.

Housed in an old church, this hunting museum holds a collection of mythical bird-rabbit creatures.

This small town in Germany was once a center of peppermint production, and has the museum to prove it.

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

This abandoned Croatian stronghold never saw a great deal of conflict but it is still a beloved relic nonetheless.

Austria's very first and only nuclear power station was completed but never used.

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

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

This military tunnel dates back to World War II and provides visitors with a little wartime adrenaline.

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

The only gulag ever to exist in socialist Yugoslavia.

This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

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

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

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

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

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

Yugoslavia's biggest underground airport lies in ruins.

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

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