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

Of all the houses that grace this neighborhood, only one is a testament to surreal architecture.

A former top secret nuclear fallout shelter now operates like a hotel stuck in the Cold War.

Mummified monks and the accidentally interred, in a 17th-century crypt.

Europe's second largest ossuary wasn't discovered until 2001.

Museum dedicated to the terror regimes of Hungary.

Once the home of a hermetic monk, this cave now houses a small church.

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

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

A heavily politicized roundabout discussing the state of a heavily politicized country.

This extensive collection covers thousands of years of Polish military history.

This enormous 32-foot painting depicts Poland's greatest medieval battle in glorious detail.

This biographical museum honors the groundbreaking scientist at her birthplace in Warsaw.

A statue honors the children who fought Nazis in Poland.

This hidden collection of everyday objects illustrates life within communist Poland.

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

The hidden lair of an alchemist rediscovered in a 2002 flood.

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