Halki Castle is located on the hill of St. Nicholas over the old village of Halki. It was built by the Knights of St. John in the 14th-15th century over the ancient Hellenistic citadel. From there they were able to control the sea routes, the harbor and the Trachean peninsula. Inside the castle are the ruins of the medieval church of St. Nicholas. At the gate the emblem of the Grand Master of the knights Pierre d’Aubusson (1476-1503) is engraved.
Today, the castle is accessed through a paved path from where the view is just fascinating. The back side of the hill is rough and its slopes lead to the sea. At the foot of the castle, there are three small chapels dedicated to Virgin Mary, to Saint Nicolas, and to the Holy Trinity.
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.