Ceiling mosaic

The dome is decorated with mosaics belonging to two phases of work, thus reflecting the apparently swift changes that occurred with the introduction of all-gold backgrounds and the loss of three-dimensional representation. The centre of the dome is dominated by a medallion of the Baptism, which is encircled by a ring of Apostles processing towards a jewelled throne surmounted by a jewelled cross. The Baptism, and the figures of Sts Peter and Paul flanking the throne and of an anonymous Apostle standing next to Paul, belong to the first phase. They are depicted in an illusionistic style; their faces and garments reveal bolder modelling and warmer colouring than those of the remaining nine Apostles.

Clear breaks in the mortar also show that the rest of the ring was completed by a second team of mosaicists. The forms and draperies of the nine Apostles are much stiffer, as if frozen into immobility. The group of mosaicists responsible for this stylistic change in decoration evidently helped to decorate Sant'Apollinare Nuovo and the Archiepiscopal chapel, which were also erected under Theodoric, and may also have had a hand in San Vitale. There can be little doubt that this group contained, or was dominated by, artisans who had been trained in the East as is suggested by the use of silver tesserae, which reflect light more sharply than those containing gold foil, and of natural stone with delicate hues for the depiction of human skin.