Cefalù is located on a bay on the northern coast of Sicily, with the cathedral situated along the water at the foot of a cliff. Roger II founded the cathedral, dedicated to the Saviour and SS Peter and Paul, likely on the site of an earlier church, in 1129. A inscription once set into the wall behind the main alter recorded that the church was completed between 1131 and 1148, an a mosaic inscription in the apse also records the latter date. Discrepancies in the height between the nave and the choir, and ambiguous documentation, however has led to controversy over dating various portions of the church.
The western elevation of the cathedral has two square towers, projecting beyond the aisle walls, that flank a triple-arched portico rebuilt in 1471. The walls are constructed of a gray-brown tufa, with blueish-gray limestone on the lower parts. The plan of the cathedral is of an aisled basilica, with a nave of seven bays with a pointed arcade set on columns, a slightly projecting transept, and a two-bay, rib-vaulted sanctuary. The white marble and granite columns of the main arcade are spoila.
Like the duomo at Monreale, the cathedral at Cefalù is primarily known today for its mosaic decorations. Here, the mosaic decoration is limited to the apse and presbytery, though is considered some of the most beautiful in Sicily.
The interior of the cathedral was considerably restored in the 16th and 17th centuries, and a comprehensive restoration of the mosaics took place from 1857-1868.