A somber memorial honors the hundreds of thousands of lives lost at this labor and extermination camp.

On this Polish road, an optical illusion makes cars seem to roll uphill.

A stone in Wolin, Poland, marks the possible location of a legendary Viking fortress.

This grubby wall is said to be one of the Earth's esoteric energy centers.

This picturesque castle in Poland has a rich history, including a legend that ties it to lost Incan treasures.

This 13th century Gothic brick castle is the largest in the world by surface area.

At first glance, this area seems like just another city park, but the lush landscape hides a dark past.

Deep in a Polish forest, this collection of Iron Age megaliths still holds onto many of its ancient secrets.

Polish luminaries and masterful folk art find sanctuary in this unique cemetery.

These massive moving sand dunes have swallowed an entire village and are still on the run.

Naturally formed rock city in Poland.

This 700-year-old structure is one of the most unique architectural and historic monuments in Gdańsk.

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.

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

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

A former mental hospital founded in the 1930s by a eugenicist who advocated for the forced sterilization of patients.