The Baptistery is crowned by a magnificent mosaic ceiling. It was created over the course of a century in several different phases. The oldest parts are the upper zone of the dome with the hierarchy of angels (2,3), the Last Judgment on the three western segments of the dome (1) and the mosaic above the rectangular chapel on the western side. An inscription in the mosaic above the western rectangular chapel states the date of the beginning of the work and the name of the artist. According to this inscription, work on the mosaic began in 1225 by the Franciscan friar Jacobus. The artist was previously falsely identified to be the Roman mosaicist Jacopo Torriti, who was active around 1300. In accordance with his style, Jacobus was trained in Venice and strongly influenced by the Byzantine art of the early to mid-thirteenth century. Since the inscription also names Emperor Frederick II, the inscription and the completion of the first phase of mosaics must fall within the Ghibelline phase of Florentine rule between 1238 and 1250.