Radzyn Chelminski was the seat of the Teutonic Knights' Commandry. The castle is one of the oldest castles built by the Teutonic Knights, built in the 13th century. In 1446 the castle went into Polish control, in 1628 during wars with the Swedes the castle was partially devastated, slowly turning into a ruin.
Currently you are still able to see the tower - damaged by artillery fire. In 1780 Prussian authorities ordered to deconstruct whatever is let of the castle. Bricks from the three wings of the castle were used to build houses for the nearby community. The castle's deconstruction was stopped towards the end of the 19th century.
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.