This space age health spa looks like a supervillain's lair.

An homage to the medieval rulers of Bulgaria.

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

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

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

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

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

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

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

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

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

A striking symbol of the Bulgarian capital.

UNESCO-protected ancient burial ground.

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

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

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

This historic black and white monastery is one of Bulgaria's architectural jewels.

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

An abandoned saucer-shaped monument in the Bulgarian mountains.

Thousands of well-dressed mummies below a monastery.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

A church of bones, decorated with 40,000 human skeletons.

A little sculpture with a large wardrobe.

Climb inside an iron crystal magnified 165 billion times its normal size.