Erected in 1154 as a notable example of the Arab-Norman architecture which flourished in Sicily under Norman rule on the island, the Church of San Cataldo is annexed to that of Santa Maria dell'Ammiraglio. In the 19th century it was restored and brought back to a form more similar to the original medieval edifice.
The church has a rectangular plan with blind arches, partially occupied by windows. The ceiling has three characteristics red, bulge domes (cubole) and Arab-style merlons. The church provides a typical example of the Arab-Norman architecture, which is unique to Sicily. The plan of the church shows the predilection of the Normans for simple and severe forms, derived from their military formation. Moreover, the building shows how international the language of Norman architecture was at the time, as the vocabulary which marks parts of the church, like the bell tower, can be tracked down in coeval buildings like the cathedral of Laon and the Abbaye aux Dames in Caen, both in Northern France, or the cathedral of Durham in England. At the same time, the church shows features shared by Islamic and Byzantine architecture, such as the preference for cubic forms, the blind arches which articulate the external walls of the church and the typical spherical red domes on the roof.
The interior has a nave with two aisles. The naked walls are faced by spolia columns with Byzantine style arcades. The pavement is the original one and has a splendid mosaic decoration. Also original is the main altar.
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.