The remarkably well-preserved final resting place of a powerful ancient Thracian king.

A collection of art from Bulgaria's time as a communist state.

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

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.

"Unity, Creativity, Beauty."

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

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

This once-grandiose behemoth of a monument from the socialist era now sits quiet and closed up.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

An abandoned saucer-shaped monument in the Bulgarian mountains.

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

A marvel of Byzantine engineering under the streets of Istanbul.

There's nothing creepier than a cemetery next to a clown motel.

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

The spectacular Roshen Fountain show lights up the night sky all summer long, until it "hibernates" under the ice waiting for spring to come.

An abused and forgotten metropolis, abandoned for centuries.

Mysterious standing stone formations looks like a petrified forest.

Last remaining nuclear missile base in Ukraine.

Temple complex that once housed the famous statue of Nike.

Unfinished monument to peace between Turkey and Armenia, long divided by a dispute over genocide.

Oriental bazaar in the heart of Sarajevo.

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

An autonomous republic of Orthodox monks.