During the Middle Ages, an Old Prussian fort called Malcekuke was located near the current site of Pieniężno. The Teutonic Knights built an Ordensburg castle near Malcekuke in 1302. Both the castle and the town which developed nearby were destroyed during the war between the Teutonic Order and the Kingdom of Poland in 1414. During the Thirteen Years' War, Mehlsack surrendered to the Order, and the castle burned down during Poland's recapture of the town. From 1589-1599, Prince Andrew Cardinal Báthory of Transylvania, cousin of Sigismund Báthory, was the administrator for the castle. In 1550, the Prussian army laid siege to the city and partially burned it down.
The town was captured by Swedish troops in 1626 during the Polish-Swedish War of 1625-29, recovered by Hetman Stanisław Rewera Potocki, and then had its castle partially destroyed by Swedish troops in 1627. The castle was restored in 1640 with Baroque gables, and its function changed from being a fortress to being a château.
During the 19th and 20th centuries the castle lost some of its Gothic and Baroque features, and in 1870 its eastern and southern wings were demolished after extensive deterioration. The remainder of the castle was used as administrative offices for Prussianofficials. From 1920-31 the western wing was renovated so the castle could be used as a school and museum. In 1945, Mehlsack, including its castle, was 90% destroyed by fighting during World War II and was conquered by the Soviet Red Army from Nazi Germany.
References:The Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.