Nine centuries-old fortresses guard the walls of this medieval Romanian city.

Even drowned in an ocean of toxic waste, the remnants of this Romanian village stand tall.

Crossing a suspension bridge above a forest is the only way to reach this 12th-century monastery.

UNESCO-protected ancient burial ground.

The site of many battles and tragedies, including the 40 maidens who leapt into the sea.

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

Legions of Roman soldiers bathed in this ancient spa complex under a Budapest transit station.

A Trabant car, a kangaroo statue, and a plethora of plants take over this abandoned-factory-turned-bar.

The abandoned "Red Star Train Graveyard" is the final rusting place for precious artifacts of train history.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

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

Trimmed trees grow alongside the graves like topiary tombstones.

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

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

A forgotten monument to Yugoslavian freedom.

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

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

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

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

Longest fortress system anywhere in Europe.

The remains of a sunken military ship wreck visible through clear water.

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

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

A musical instrument played by the sea.