"Unity, Creativity, Beauty."

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.

A striking symbol of the Bulgarian capital.

Sofia's legislative center is continuously reinventing itself.

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

UNESCO-protected ancient burial ground.

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

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

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

An abandoned saucer-shaped monument in the Bulgarian mountains.

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

An homage to the medieval rulers of Bulgaria.

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

Where Stoddart and Connolly suffered in the infamous Bug Pit.

This "tower of death" has acted as an observatory, a religious hub, and an executioner's lair.

Light still pours into the ruins of this ancient Islamic observatory.

The Avenue of Mausolea is a series of grand palatial tombs.

An abandoned 17th-century baroque hunting lodge with a wonderfully strange architectural plan.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

A symbol of friendship between the mountainous regions of Switzerland and Bhutan.

For centuries no one knew there were hundreds of bones and precious artwork hidden beneath this Swiss church.