A castle-like sea fort from the 17th century is now a museum to oyster farming.

Three underground crypts and a pointed arch under the bell tower make this cathedral unique among Romanesque churches.

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

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

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

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

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

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

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

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

A striking symbol of the Bulgarian capital.

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

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

At this 16th-century monastery in rural Bulgaria, visitors can also spend the night.

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

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

Mysterious standing stone formations looks like a petrified forest.

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

Crossing a suspension bridge above a forest is the only way to reach this 12th-century monastery.

On a small island, a replica of a Finnish village from the Iron Age.

A giant gorilla made of used car tires used to sit sentinel over a Helsinki college campus.

Extraordinary animals sculpted from leftover junk.

The last permanent exhibit dedicated to the Soviet leader.

Explore the frozen river and take a walk to a nearby island on some of the longest ice roads in Sweden.