The decoration of this church, which was very rich, disappeared almost completely, except for some fragments of marble in the presbyterium and, above all, a beautiful floor in opus sectile made with colored marbles worked in cloisonné technique, where human and animal figures are represented. Moreover, fragments of colored glass suggest that the windows of this church were once made of stained glass bearing figures of Saints. The mosaics of the interior, representing the apostles and the life of Christ, were still visible - although defaced - in the 18th century.