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.
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Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.