The raised choir and presbytery contain a magnificent Romanesque pulpit and screen made in 1207. The apse is dominated by a great mosaic dating from 1297, which depicts the same subject as that on the façade and is probably by the same unknown artist. The crucifix above the high altar is attributed to Luca della Robbia. The sacristy is decorated with a great fresco cycle on the Life of St Benedict by Spinello Aretino (1387).