This huge metal monument is slowly being stripped to its concrete skeleton.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

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

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

An ethereal glowing blue ocean cave in Croatia.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A musical instrument played by the sea.

An homage to the medieval rulers of Bulgaria.

Sofia's legislative center is continuously reinventing itself.

The temple that withstood the Nazis.

A vast Communist-era exhibition space in the Bulgarian capital.

Said to be the only museum in the world dedicated to the most classic of all blooms, the rose.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

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

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

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

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

"Unity, Creativity, Beauty."

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

Mysterious standing stone formations looks like a petrified forest.

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

Rock carving created 1,300 years ago 75 feet off the ground.

Eastern Bloc nostalgia, anybody?

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