This lonely minaret with an unusual decorative symbol is all that remains of a historic Ottoman mosque.

A 14th-century Serbian Orthodox church that was once converted into a mosque under the much-disfavored Ottoman Empire.

The site of a legendary 14th-century battle and a controversial 20th-century speech.

An unfinished Serbian Orthodox church with 1,389 golden crosses planned to represent the Battle of Kosovo.

These abundant, over-the-top monuments are so widely scattered that they define the entire compact capital cityscape, often leading to jokes about whether there are more statues than residents.

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.

This building has two facades of clashing architectural designs.

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

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

"Unity, Creativity, Beauty."

A striking symbol of the Bulgarian capital.

A flamboyant five-story building in Bulgaria resembles a crawling snail.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

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

A fountain standing as a testament to a doomed alliance.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

This crucial gathering spot along the "hippie trail" still displays old notes between traveling beatniks and backpackers.

This museum was invented in a novel before being made real by the author.

The most metal church of all time was built in record time because of an international, pious pissing contest.

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

Step back in time and witness the fall of Constantinople.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

A sixth-century Byzantine cistern hidden below a modern carpet store.