An homage to the medieval rulers of Bulgaria.

Sofia's legislative center is continuously reinventing itself.

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

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

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

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

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

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

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

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.

In a long-dry lake bed, these groups of massive stone pillars bear a striking resemblance to clumps of everyone's favorite fungi.

A striking symbol of the Bulgarian capital.

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

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.

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

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

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

The Swedish flag over this small naval fort signals that the nation is at peace.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

Stockholm's deepest subway station is also a stunning ecological wonder.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.