Palermo Cathedral was erected in 1185 by Walter Ophamil (or Walter of the Mill), the Anglo-Norman archbishop of Palermo and King William II's minister, on the area of an earlier Byzantine basilica. By all accounts this earlier church was founded by Pope Gregory I and was later turned into a mosque by the Saracens after their conquest of the city in the 9th century. Ophamil is buried in a sarcophagus in the church's crypt. The medieval edifice had a basilica plan with three apses, of which only some minor architectural elements survive today.
The upper orders of the corner towers were built between the 14th and the 15th centuries, while in the early Renaissance period the southern porch was added. The present neoclassical appearance dates from the work carried out over the two decades 1781 to 1801, supervised by Ferdinando Fuga and Giuseppe Venanzio Marvuglia. During this period the great retable by Gagini, decorated with statues, friezes and reliefs, was destroyed and the sculptures moved to different parts of the basilica. Also by Fuga are the great dome emerging from the main body of the building, and the smaller domes covering the aisles' ceilings.
In the right aisle, in the first and second chapel communicating with one another, are the monumental tombs of King Roger II, his daughter Queen Constance I of Sicily, her husband Emperor Henry VI, and their son Emperor Frederick II, as well as the burials of Frederick's first wife Constance of Aragon and his great-great-grandson William II, Duke of Athens on the side walls.
Palermo Cathedral is part of the UNESCO World Heritage Site of Arab-Norman Palermo and the Cathedral Churches of Cefalú and Monreale.
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.