An Art Nouveau gem hides beneath the layers of city grime obscuring this once-magnificent building.

Roman ruins, natural methane fires and a lovely beach.

Flames have been burning within this mountain for more than 2,500 years.

Ottoman-era houses lovingly preserved.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Ancient serpentine sacrifice holder that has stood the test of time.

No one is sure if the world's fourth-largest diamond had been found in a rubbish heap or was pawned by Napoleon's mom.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A marvel of Byzantine engineering under the streets of Istanbul.

Sofia's legislative center is continuously reinventing itself.

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

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

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.