Malbork Castle

With the high castle towering far above the bastions and walls and the grand master's palace, the Marienburg (Malbork) still impresses its viewers today. The builder was the Teutonic Order, which the Polish Duke Conrad of Mazovia brought into the country in 1225 in the fight against the pagan Pruzzi. Malbork Castle, which rises on an embankment on the right bank of the Nogat, is the world's largest brick castle. Its fortifications cover an area of 20 hectares.

Source: Polish Online

"The Malbork Castle is a medieval Teutonic Order castle built in the 13th century, located on the Nogat River, a branch of the Vistula River, near the Polish city of Malbork (German: Marienburg).
From 1309 to 1454 the castle was the seat of the grand master of the order in the state of the Teutonic Order. After that, with brief interruptions from 1457 to 1772, it belonged to Polish-Prussia, a province of the Polish Kingdom, and served as the residence of Polish kings. At times, the castle was also under Swedish control. After the partition of Poland, the castle came to the Kingdom of Prussia in 1772 and after the Second World War to Poland. The spacious castle complex is the largest brick building in Europe. The UNESCO World Heritage site houses several exhibitions and can be visited all year round on snow-free days." Wikipedia - Marienburg (Ordensburg)

This castle is without question a highlight. If you are even remotely close by, you should definitely stop by here.
You won't get back such old history in a hurry.

Was really impressed. Very interesting castle complex - which was painstakingly rebuilt after the destruction in World War II.