It is accessed via a late Baroque style staircase. The façade shows two mosaics of the Monreale school of 1960 depicting Christ on the throne flanked by the figures of St. George and St. Demetrius. The building has three naves, separated by two rows of seven marble columns. An imposing wooden iconostasis covers the three apses. The main apse, initially facing east according to the Byzantine canon, was relocated towards the west in the 1500s reconstruction. Between 1641 and 1644 Pietro Novelli painted the frescoes in the apses. In the central one the Exaltation of the Trinity is represented, in the right one Christ ascending to heaven. In the left aisle there is a large oil painting on canvas (D'Antoni A., 1845) depicting St. Nicholas giving his goods to the poor. The oldest work of greatest artistic importance is the Icon of Christ with Mary of the Sienese school of 1500, the only one painted with egg tempera. On the right wall, with respect to the main entrance, is the tomb of Father G. Guzzetta, one of the most illustrious men in Piana. Following new restorations (1960) the choir was transformed and enlarged and the barrel vault of the central nave replaced with a coffered roof with gold decorations. The signs of two styles are evident in the church: a western one, represented by the frescoes by Novelli and by various paintings on canvas; the other oriental, attested by the iconostasis and the icons placed in the side aisles. Recently the cathedral has been embellished with new frescoes.