First mentioned as Soban, Sobień Castle was a Royal castle guarding the merchant route along the San River. The castle was built by order of King Casimir the Great in 1340. In 1389 Władysław II Jagiełło conferred the castle to a noble family of Kmita.
The castle was destroyed in 1474 and again in 1512 by Hungarian forces. In 16th century the Kmita family sold the estates and the castle to Stadnicki family, who held it until 1713.
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.