The master builder or architect Giovanni Panittera was responsible for the cathedral’s elevation, as confirmed by an inscription next to the large window on the western façade, dated 1240: “Anno dominice Incarnationis, MCCXI, mense Augusti, XIII indictione, per manum Iohannis Panicterae”.
Panittera certainly took care of the decoration, consisting of blind arches with intertwining rings in the first order, and a series of small arches with recessed rings in the second order, ending with a notched cornice. It is likely that the entire composition, including the small columns and the sculptures of the capitals, can be attributed to him.