The pictorial decoration is located on the entire surface of the apse half-cylinder. The zenithal motif consists of two superimposed squares that form an eight-pointed star, around which we find decorative motifs with peacock feathers and a large laurel wreath. Below this geometric central decoration is the best-preserved record, with scenes relating to the passion of Christ. Some of these are visible to the faithful from the cathedral nave (arrest of Christ, denial of St. Peter and delivery of the keys, scenes of St. Paul) and others only from inside the apse itself (Crucifixion of Christ, death of Absalom). The second concentric register houses a representation of the enthroned Virgin flanked by apostles and prophets.