The church was erected in 1185 by Walter Ophamil, the Anglo-Norman archbishop of Palermo and King William II's minister, on the area of an earlier Byzantine basilica. This earlier church was founded by St. Gregory and was later turned into a mosque by the Saracens after their conquest of the city in the 9th century. Ophamil is buried in a sarcophagus in the church's crypt. The medieval edifice had a basilica plan with three apses, of which only some minor architectural elements survive today.