Malbork Castle is a medieval Teutonic Order castle from the 13th century, then called Marienburg. This castle is the largest in the world in terms of the area it occupies, and at the time it was completed, it was the largest castle built of bricks. The complex contains the High, Middle, and Lower Castles. UNESCO added Malbork Castle to the World Heritage Sites list in 1997, but the castle has been under various types of state protection since the 19th century. You can track your visit via a GPS device that guides you through all the chambers and prevents you from getting lost.