This spaceship-like Serbian monument reaches for the stars in celebration of the fallen fighters of fascism.

Structure built from the skulls of vanquished foes.

This 14th century castle withstood years of battle but is now sliding off the hills into the Danube.

On the outskirts of the small village, an abandoned grassy field glitters thanks to the white stones of an ancient structure.

Underneath this Byzantinian church lies a necropolis filled with ancient tombs and the ruins of previous churches.

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

Not far from a popular beach, an unfinished, abandoned mansion for Bulgaria's last communist dictator.

An unfinished complex built for children from around the world sits abandoned on the Black Sea coastline.

The social hall of this former factory is a Communist-era time capsule.

An homage to the medieval rulers of Bulgaria.

"Holy Wisdom" overlooks the city that became its namesake.

This massive stone and steel monument remembers a century-old battle that cost thousands of lives and nearly destroyed the city.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

Ruins of an early Roman Christian church dating back to the 4th to 5th centuries.

Outstanding, eerie frescoes and decorations fill this 19th-century monastery.

An ancient Thracian city where fire rituals were practiced on the largest cult altar in Southeast Europe.

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

A mysterious tunnel hidden in the shadows of a colorful, historic sanctuary.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

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

"Unity, Creativity, Beauty."

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

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

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