The Mandraki was the military harbour and was guarded by a tower built between 1464 and 1467 by the Grand Master Zacosta at the end of the natural mole. After the siege of Rhodes in 1480 the Grand Master d'Aubusson added a bastion around the tower transforming it into a guard fortress on the sea.
The castle was built at the place of an old Byzantine church dedicated to St. Nicholas, hence the name. Since the 17th century, a lighthouse was added at the top.
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.