"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.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

Gargoyle head that brings good luck.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

Natural rock formations resembling monks in hats inspire folk legends.

The site of many tense prisoner exchanges across the Military Demarcation Line between North and South Korea.

South Korea's largely symbolic, barely used gateway to the North.

South Korea's women of the sea have completely flipped their society's structure by becoming revered fisherwomen.

South Korea's only sex-themed park.

Secret North Korean passage discovered below the world's most dangerous border.

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.

Late at night, the bust of the "Dracula" actor was snuck onto the facade of this Budapest castle.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

Where commuters walk through remnants of an ancient Greek necropolis.

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

150 or so scrounged-up lamps, chandeliers, and lanterns light up this alley in central Athens.

The hallucinogenic center of the ancient world.

The world's smallest park was dedicated in 1948 as the only colony for leprechauns west of Ireland.

An unassuming grey box sitting on San Francisco's Pier 17 is a "sky diary" of the coastal city's temperamental weather.