This church is a precious and very rare example of mix between County architecture and Monarchy architecture. It shows compositional and structural experimentalism. In fact, even if there exists a document which attests the construction of the Basilian monastery of the Saints Peter and Paul built by Count Ruggero the Great (1116), equally one can read (in Greek on the flat arch that sustains the tympanum of the entrance portal) a subsequent renewal of the building by the master in the art of construction ("Protomaster") "Gerard le Franc" dated 1172. (In the latin and greek sources in south Italy, Normans are often identified by the name "Francs".) The basilicas plan, with three naves, in axis with the apses, is made by four Byzantine centred modules (two with cupolas) which are along the longitudinal axis, without transept and projecting arms. The corner joints of the octagonal structures, which mediate the cupolas with the squares of the basis, are also original: almost a synthesis between mouqarnas and niches a rincassi. Despite these eastern aspects, the church shows, above all from the outside, various references to the Norman architecture, like the polychromatic decorations, the battlements, the pilasters which have counterfort function, the small scalar towers which close the prospect. The pictures show the apses, the lateral portal and the inside of the central cupola.
Guido Di Stefano, "Monumenti della Sicilia Normanna", Palermo, 1979
Melo Minnella Palermo