The main mosaic depicts Christ enthroned with Our Lady at his right hand, flanked by saints and popes. The Hand of God emerges from a wreath above His head. On the left side are Pope Innocent II, holding a model of the church identifying him as the builder, St Lawrence and Pope St Callixtus. Below the epigraph is a frieze with the Lamb of God and the Twelve Apostles represented as a herd of sheep in procession.