Built starting from 1172 at the behest of William II of Altavilla, king of Sicily from 1166 to 1189, it is famous for the rich Byzantine mosaics that decorate its interior. In August 1926 Pope Pius XI elevated it to the dignity of a minor basilica.[4] Since 3 July 2015 it has been part of the World Heritage (UNESCO) as part of the Arab-Norman itinerary of Palermo and the cathedrals of Cefalù and Monreale.
