It is one of nine structures included in the UNESCO World Heritage Site known as Arab-Norman Palermo and the Cathedral Churches of Cefalù and Monreale.

[1] According to tradition, the building was erected after a vow made to the Holy Saviour by the King of Sicily, Roger II, after he escaped from a storm to land on the city's beach.

Construction began in 1131, the apse mosaics were begun in 1145, and the sarcophagi that Roger II provided for his tomb and that of his wife were put in place the same year.

[citation needed] The façade is characterized by two large Norman towers with mullioned windows, each surmounted by a small spire added in the 15th century.

The interior of the cathedral is on the Latin cross plan, divided into a nave and two aisles by arcades of antique columns: fourteen in pink granite and two in cipolin.

Beyond the crossing, the church is unusual in combining a style that is essentially Romanesque in its massive simple forms with the Gothic pointed arch.

The two lower side apses have the upper tiers of the exterior decorated by blind arcading of small crossed arches and sculpted corbels, also seen used extensively at Monreale.

The dominant figure of the decorative scheme is the bust of Christ Pantokrator, portrayed on the semi-dome of the apse with a hand raised in Benediction.

In the upper tier of the apsidal wall is depicted the Blessed Virgin Mary, her hands raised in obsecration, flanked by four archangels.

The basilica houses several funerary monuments, including a late Antique sarcophagus, a medieval one, and the notable sepulchre of the Bishop Castelli of the 18th century.

The church also houses a canvas of the Madonna from Antonello Gagini's workshop (16th century) and a painted wooden cross by Guglielmo da Pesaro (1468).

Starting in 1985, the Palermo artist Michele Canzoneri was commissioned and has installed 72 modern, abstract, stained-glass windows based on episodes from the Old and New Testaments.

They depict a dove drinking, parts of two other birds, two small trees, and a lily-shaped flower, enclosed in a frame with ogival and lozenge motifs.