Starý zámok (literally Old Castle) is well preserved castle complex built in the 15th and 16th centuries. It was embedded to the church of Our Lady from the 13th century. The first documented mention dates from 1486. The church was damaged by earthquake in 1443 and the reconstruction to the fortress was made between 1495-1515 against the Turkish threat. The last significant restoration on the defense complex was carried out in 1777.
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.