The Hall, that was designed to be used for receptions and official ceremonies, was decorated by the school of Raphael on the basis of drawings by the artist, who died prematurely before completion of the work (1520). It takes its name from Constantine (306-337 A.D.), the first Christian emperor to officially recognize the Christian faith, granting freedom of worship. On the walls are painted four episodes of his life which testify to the defeat of paganism and the triumph of the Christian religion: the Vision of the Cross, the Battle of the Pons Milvius, the Baptism of Constantine and the Donation of Rome. The decoration of the Hall is completed by figures of great Popes flanked by allegorical figures of Virtue. The original wooden roof which Leo X (pontiff from 1513 to 1521) had built was replaced under Gregory XIII (pontiff from 1572 to 1585) by the modern ceiling, the decoration of which was entrusted by order of the Pope to Tommaso Laureti who portrayed the Triumph of the Christian religion in the central panel. The work was completed at the end of 1585 under Pope Sixtus V (pontiff from 1585 to 1590).
Recently conducted restoration work on the walls of the Hall has confirmed Raphael's authorship of the figures of Comitas and Iustitia, painted in oil on the wall using an experimental technique, to the right of the Vision and the Battle respectively.