The archiepiscopal palace and monastic buildings on the south side were of great size and magnificence, and were surrounded by a massive precinct wall, crowned at intervals by twelve towers. This has been mostly rebuilt, and but little now remains except ruins of some of the towers, a great part of the monks'
dormitory and
frater, and the splendid
cloister, completed about 1200. The latter is well preserved, and is one of the finest European cloisters extant both for its size and the beauty of its detailing. It is about 2,200 m2, with pointed arches decorated with
diaper work, supported on pairs of columns in white
marble, 216 in all, which are alternately plain and decorated with bands of patterns in gold and colors, made of glass
tesserae, arranged either spirally or vertically along each shaft. The marble capitals are each carved with foliage, biblical scenes and allegories; no two are the same. At one corner, a square pillared projection contains the marble fountain or monks'
lavatorium. The plan of the church is based on models of
Clunian origin from northern France. The facade is flanked by two towers, like
Cefalù Cathedral, while the large three-apse choir is similar to one of the first three-apse churches. The basilican
nave is wide, with narrow
aisles. On each side, columns of grey oriental granite (except one, which is of
cipolin marble) support eight pointed arches much stilted. The capitals of these (mainly
Corinthian) are also of the classical period. There is no
triforium, but a high
clerestory with wide two-light windows, with simple tracery like those in the nave-aisles and throughout the church, which give sufficient light. The other half, eastern in two senses, is both wider and higher than the nave. It also is divided into a central space with two aisles, each of the divisions ending at the east with an apse. The roofs throughout are of open woodwork very low in pitch, constructionally plain, but richly decorated with colour, now mostly restored. At the west end of the nave are two projecting towers, with a
narthex (entrance) between them. A large open
atrium, which once existed at the west, is now completely destroyed, having been replaced by a
Renaissance portico by
Giovanni Domenico and
Fazio Gagini (1547–1569). The main internal features are the vast (6,500 m2; 70,000 sq. ft.) glass
mosaics, executed in
Byzantine style between the late 12th and the mid-13th centuries by both local and Venetians masters. The tomb of
William I of Sicily (the founder's father), a
porphyry sarcophagus contemporary with the church, under a marble pillared canopy, and the founder William II's tomb, erected in 1575, were both shattered by a fire, which in 1811 broke out in the choir, injuring some of the mosaics and destroying all the fine walnut choir-fittings, the organs and most of the choir roof. The tombs were rebuilt, and the whole of the injured part of the church restored a few years after the fire. The present organ, revised in 1967 by Ruffatti, has six manuals and 102 stops. On the north of the choir are the tombs of
Margaret of Navarre, wife of William I, and her two sons Roger and Henry, together with an urn containing the
viscera of
Saint Louis of France, who died in 1270. The pavement of the triple choir, though much restored, is a specimen of marble and porphyry mosaic in
opus alexandrinum, with signs of Arab influence in its main lines. The mosaic pavement of the nave was completed in the 16th century, and has disks of porphyry and granite with marble bands intermingled with irregular lines. Two
Baroque chapels were added in the 17th and 18th centuries, which are shut off from the rest of the church. The bronze doors of the mosaic-decorated portal on the left side was made by
Barisano da Trani in 1179. ==Gallery==