The Castle of the Teutonic Order in Malbork is the largest castle in the world by surface area. It was built in Marienburg, Prussia (now Malbork) by the Teutonic Knights, a German Roman Catholic religious order of crusaders, in a form of an Ordensburg fortress. The Order named it Marienburg (Mary's Castle). The town which grew around it was also named Marienburg.
The castle is a classic example of a medieval fortress and, on its completion in 1406, was the world's largest brick castle. UNESCO designated the "Castle of the Teutonic Order in Malbork" and the Malbork Castle Museum a World Heritage Site in December 1997. It is one of two World Heritage Sites in the region with origins in the Teutonic Order. The other is the "Medieval Town of Torun", founded in 1231 as the site of the castle Thorn (Torun).
Malbork Castle is also one of Poland's official national Historic Monuments (Pomnik historii), as designated September 16, 1994. Its listing is maintained by the National Heritage Board of Poland.