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.

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

An abandoned saucer-shaped monument in the Bulgarian mountains.

Dive for drinks at Croatia's first and only underwater winery.

Just a few miles from Novalja, a strange geological oddity has left scientists baffled.

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

Built as an anti-fascist tribute, this surreal Yugoslav memorial became an unwelcome symbol after the Croatian war for independence.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

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

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.

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

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

This former estate of a fascist leader is now a burnt out ruin leading to a system of secret tunnels.

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

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

Yugoslavia's biggest underground airport lies in ruins.

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

This abandoned Greek island was the last active leper colony in Europe.

A minotaur, a labyrinth, and a dubious restoration pull in visitors from around the world.