This church was built during the period of the Countess Adelasia and the Count Ruggero. It has only one nave and three apses, with a length equal to three times the transverse dimension. Symbolically represented is the mystery of the Trinity: the three small windows of the apses have their axes converging towards one central point. The same symbolism, stressed by the sunbeams, is represented by the three small windows that overhang the area of the presbytery. The lateral portal and the apses with pilasters (counterforts) relate to models of early Norman architecture. The picture shows the apses with the pilasters upholding the cone-like ceilings.
Lojacono Pietro, " L'Abbazia di SantoSpirito presso Caltanissetta", Palladio I-III n.s. anno IV, Roma, 1954
Divita Antonino, " Appunti sulla Abbazia di SantoSpirito presso Caltaniss", Siculorum Gymnasium1, pp.106-115, Catania, 1949
Melo Minnella Palermo