The first development at Scicli was around the Castello dei tre cantoni at the top of San Matteo hill that overlooks the town. The Castello dei tre Cantoni is actually composed of two separate fortifications, the Castelluccio higher up and the Castellaccio at a lower level.
This was a defensive structure that, over the centuries, was enlarged and used first by the Arabs, then by the Normans and then later as a military outpost of the County of Modica. The current castle is dated to the 13th century although studies date its origins to the first half of the 12th century.
The Castle has a triangular tower, while to the north-east stands a large wall terminating in a quadrangular tower. The reason for having an unusual triangular tower is unknown, but thought to be symbolic (possibly related to the three points of Sicily itself) rather than a military function.
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.