The exquisite mosaics in the apse of Santa Maria in Trastevere date back to 1140.
In addition to the emblems of the four Evangelists, the triumphal arch also depicts the Old Testament prophets, Isaiah and Jeremiah. Above each prophet is a small cage with a bird inside. This image symbolises Christ imprisoned by the sins of man.
In the semi-dome Christ and the Virgin Mary sit side by side on the same throne. To the right are saints Peter, Cornelius, Julius and Calepodius, and to the left, saints Calixtus and Lawrence. The figure on the far left holding a model of the church is Pope Innocent II (r. 1130-43).
The six mosaics (c. 1291) below the frieze of lambs are by the Roman painter and mosaicist, Pietro Cavallini (c. 1250-c.1330). They illustrate scenes from the life of the Virgin Mary, ranging from her birth to her death.