The dome was decorated originally with a fresco then later with mosaic. After a fire these were replaced with a nineteenth-century reproduction, with the same iconography as the original if not the stylistic qualities. It depicts the twenty-four elders of the Apocalypse bearing crowns and standing around the base of the dome. Above the main altar, and facing the royal throne, is an image of Christ in Majesty. The upper gallery of the chapel was the royal space, with a special throne area for the king, then emperor, which let onto the liturgical space of the church and onto the atrium outside as well.