A beautiful wooden ceiling and an extraordinary marble floor, framed by the Chapels of the Apostles along the two side aisles, dominate the sumptuous and stylish appearance of the main nave.
The painter Daniele Schmidt recreated the ceiling, after the 1943 fire. He tried to reproduce the original decorations.
It is made of painted wood in Arab-Byzantine style, with various shades of sky-blue, green, yellow, gold, red, orange and turquoise.
The central part of the main nave and of the transept are decorated with small-star shaped sunk cupolas, an Arab reference to the firmament.
It presents different figures of Saints, Angels, the Madonna, Jesus Christ, the four Evangelists and Old and New Testament characters.
The huge hanging chandelier in the nave is a post-war reproduction of the one that was a gift from the Bourbon, King Ferdinand II, in 1847.
The marble floor was created by Giovanni Angelo Montorsoli, a pupil of Michelangelo, in the second half of the 16th century. The actual floor is a faithful post-war reproduction of the original one with a beautiful geometrical pattern.
On the triumphal arch, a mosaic represents in the centre Jesus, Saviour of the World, inspired by the painting of the same name by Antonello da Messina, in the National Gallery in London. Besides Christ are St Luke the Evangelist and Antonello da Messina. This work was done by the Vatican School of Mosaicists for the year 2000 Jubilee and is based on the sketch made by Giulio Aristide Sartorio in the 1930’s.