This imposing 20th-century castle was abandoned before it was ever completed.

Museum dedicated to "the man who moved the Earth."

An abandoned Nazi explosives plant founded by the inventor of dynamite is now an underground museum.

This uber-quaint Polish village is known for its habit of painting elaborate floral motifs on just about everything.

This Nazi ruin was the site where Hitler was almost blown up by a suitcase bomb.

A fairytale Gothic castle steeped in Nazi treasure conspiracy theories.

The site of the first battle of World War II.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

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

These plaques found across Warsaw commemorate the sites where executions or battles took place during the German occupation.

In the summer, the area around this sculpture transforms into a vibrant concert venue.

This bell stars in a tragic love tale and is said to make wishes come true.

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

A tree planted by Marie Curie is treasured by the Radium institute that she set up.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

A statue honors the children who fought Nazis in Poland.

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

Order “Proletariat’s Cutlet” at this communist-themed restaurant allegedly once visited by Lenin.

The final resting place of more than 200,000 people, this is one of the largest cemeteries in Europe.

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

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