Room in the Castle of the Teutonic Order in Malbork (Polish: zamek w Malborku; German: Ordensburg Marienburg). It is the largest castle in the world by surface area, and the largest brick building in Europe. It was built in Prussia by the Teutonic Knights, a German Roman Catholic religious order of crusaders, in a form of an Ordensburg fortress. The Order named it Marienburg (Marys Castle). The town which grew around it was also named Marienburg.