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

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

A set of seven houses, each built in a style that represents a European country.

A unique collection of gilded age mechanical pianos.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

This building has two facades of clashing architectural designs.

Founded in the 4th-century, the town of Pernik plays host to the Surva Carnival⁠—a magnificent display of masked Kukeri dancers.

An homage to the medieval rulers of Bulgaria.

One of the largest mines in Bulgaria is now home to a vast museum more than 100 feet underground.

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.

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

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

"Unity, Creativity, Beauty."

Eastern Bloc nostalgia, anybody?

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

A striking symbol of the Bulgarian capital.

A flamboyant five-story building in Bulgaria resembles a crawling snail.

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

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

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

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

An abandoned saucer-shaped monument in the Bulgarian mountains.

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