The cathedral, which at first glance looks more like a fortified Arabian palace than a Christian place of worship, is set back from Corso Vittorio Emanuele, facing a piazza that was once a cemetery. Built in yellow stone with a narrow tower at each corner, it is covered in intricate decoration that continues around the façade to the east side. The west side is joined to the Palazzo Arcivescovile by two Gothic arches. The arcaded porch which surrounds the main entrance was added in the fifteenth century, while the dome, a baroque oddity in this medieval context, was added in the eighteenth century. A picture in the Palazzo Arcivescovile by an unknown artist shows what the cathedral looked like in its original form (see below). Palm trees in the piazza, together with statues of the saints, with Santa Rosalia at the centre, complete the exotic picture. The fact that the cathedral was founded by an Englishman, Walter of the Mill, known in Sicily as Gualtiero Offamilio, makes it all the more remarkable.

Walter came to Palermo as tutor to the royal children and rose up through the ranks to become archbishop and first minister to King William II. He built such a powerful position for himself with the support of leading barons and churchmen that the king, advised by Walter’s arch-rival Matthew of Ajello, decided to create a second archbishopric and cathedral at Monreale to curb his power. Not to be outdone, Walter rebuilt the existing one in Palermo making use of Arab builders and craftsmen. Walter was archbishop from 1169 until his death in 1190, when he was succeeded by his brother Bartholomew.

The cathedral was completed in 1185, towards the end of William II’s reign, and dedicated to the Assumption of the Virgin Mary. The site had long been used as a place of worship. First there was a Christian church on the site, followed by the Arabs’ grand mosque. When the Normans took Palermo in January 1072, the mosque was restored to a Christian church and handed over to the Greek archbishop, Nicodemus. The first cathedral built here by the Normans was linked to the Palazzo dei Normanni by a street with porticoes called Via Coperta. Taken as a whole, the interior is disappointing, due to alterations carried out in the late eighteenth century, when the Norman structure was replaced with one in a neoclassical style.

The interest lies in the individual items on display. Among them from Norman and Hohenstaufen times are the tombs of Roger II, who was crowned king of Sicily in the cathedral in 1130, and his daughter Constance and her husband, the German emperor Henry VI. There is also the tomb of Frederick II, stupor mundi (‘wonder of the world’), Holy Roman Emperor and king of Sicily (the son of Henry and Constance) and Frederick’s first wife, Constance of Aragon. Artefacts discovered in the tombs include Constance of Aragon’s crown, made in the royal workshops around 1220. The crypt, which is accessed through the sacristy beyond the treasury, extends for some way below the cathedral. Historic links to the time of the cathedral’s foundation include stone tombs, some with elaborate carvings, commemorating the early archbishops. One of these bears the name of Walter of the Mill. An unusual touch is the inscription of a verse from the Qur’an, in Arabic, carved in the far left-hand column of the porch in front of the main entrance. Presumably this column was part of the material from the Arabs’ grand mosque reused when building the porch.