It is generally believed that this church dates from the time of William II (1166–1189), though some of the interior features, such as the superimposed columns set into the wall to form niches, are more reminiscent of the period of Roger II. The most beautiful aspect of the building is the external view of the apse, whose galleries, consisting of blind arches supported by delicate columns with tall dosserets, are the only example of a marriage of Siculo-Norman and Italian-Romanesque architecture. In addition to the columns, disks featuring polychrome Arab-Norman geometrical patterns made from volcanic glass lend rhythm and harmony to the gallery. The church has a Latin-cross ground plan with a nave and side aisles. The arms of the transept, of the Cassino type, project only slightly. The nave has barrel vaulting, the side aisles cross vaulting. The central part of the three-apsed chancel is covered by a cupola supported on a drum. This drum is decorated externally with a circular pseudo-gallery. Our picture shows the decorative gallery of the transept and projecting central apse.
F. Valenti, " la SS. Annunziata detta dei Catalani", Palermo, 1931
Strzygowski, "Die Baunkunst der Armeiner und Europa, Wien 1918
Melo Minnella Palermo