Macabre astrological automaton clock dating to the late 1400s.

Countless grotesque faces stare out from this eerie Prague art wall.

A Jenga-style cylindrical tower of books that appears to go on forever.

Two stunning 17th-century libraries and a cabinet of curiosities.

Ruins of an early Roman Christian church dating back to the 4th to 5th centuries.

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

Underneath this Byzantinian church lies a necropolis filled with ancient tombs and the ruins of previous churches.

Sofia's legislative center is continuously reinventing itself.

Eastern Bloc nostalgia, anybody?

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

A collection of art from Bulgaria's time as a communist state.

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

This oddly beautiful water cistern is a techno-temple to the wet stuff and a multimedia masterpiece.

A striking public sculpture representing the period of martial law in Communist Poland.

A collection of old neon signs from all over Poland line a secluded courtyard.

At night, this memorial illuminates a ghostly outline of a footbridge that connected two sections of the Warsaw Ghetto.

A bronze replica of an elm tree that honors the victims that perished in Pawaik Prison.

An artificial date palm stands as a memorial to Warsaw's Jewish community.

Atop this library is one of the most beautiful green spaces in Warsaw.

Special benches that play Chopin's music are scattered throughout his native city.

The giant statue and its model solar system honor the native Pole who declared that the Earth revolves around the Sun.