Legend says this sacred tree was a gift from goddess Athena.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A decaying, yet still functioning, work of communist architecture.

Grand Orthodox cathedral with walls filled with frescoes and icons.

A Soviet-style monument, built after transferring the remains of heroes from their graves.

A chain coffee shop in Bulgaria that takes its Italian roots very seriously.

An homage to the medieval rulers of Bulgaria.

Sofia's legislative center is continuously reinventing itself.

Rebuilt several decades ago, its striking murals prevent it from being reconsecrated as a church.

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.

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

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

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

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.

This building has two facades of clashing architectural designs.

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

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.

This nine-story building can be played like an instrument.