Château de Saint-Sauveur-le-Vicomte was built in the 11th and 12th centuries. It was besieged twice during the Hundred Years War. The city walls were breached by cannon in 1374. This is believed to have been among the first successful uses of guns against city walls in history. Today it is partially ruined, but still a notable castle with massive 14th century towers and a 12-15th century abbey.
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.