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

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

This building has two facades of clashing architectural designs.

Sofia's legislative center is continuously reinventing itself.

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

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

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

This once-grandiose behemoth of a monument from the socialist era now sits quiet and closed up.

Mysterious standing stone formations looks like a petrified forest.

A fake Transylvanian castle houses a cathedral of antlers.

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

Museum dedicated to the terror regimes of Hungary.

World's tallest cigar-shaped radio tower.

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

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.

An homage to the medieval rulers of Bulgaria.

An abandoned saucer-shaped monument in the Bulgarian mountains.

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

Thousands of letters to Santa get delivered to this mailbox in Greenland.

This once-derelict building is now one of the most beautiful bookstores in the world.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

Something's watching you.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

This snug medieval lane is one of the narrowest streets in the world.