The world's largest frame offers spectacular views of the city's past and present.

This indoor ski resort has a mountain contained inside a mall.

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

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

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

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

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

Sofia's legislative center is continuously reinventing itself.

This building has two facades of clashing architectural designs.

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 tiny park in the middle of some big power politics.

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

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

A fountain standing as a testament to a doomed alliance.

Legend says if you stick your thumb in the hole and it gets wet, your wish will be granted.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A marvel of Byzantine engineering under the streets of Istanbul.

This column celebrates Rome's victory over the Goths, and may be the oldest Roman monument in Istanbul.

An underground network of massive stone arches and their skylit vaults support ruins of portico structures above.

This elevator was built in 1907 to connect two neighborhoods separated by a steep, rocky cliff.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

These former Nazi anti-aircraft towers offer a singular view of the north of Berlin in the summer, and a sanctuary for bats in winter.