One of the cycle of 13th century frescoes in the basilica S.S. Quattro Coronati Rome.These purport to illustrate a decree issued by Constantine in the 4th century, which, after recording his miraculous cure from leprosy and conversion to Christianity, supposedly conferred his temporal powers to the pope and bequeathed Rome and the western part of the Roman Empire to the bishop of Rome and his successors. This fresco shows St Peter and St. Paul appearing in a dream to Constantine who is suffering from leprosy. They advise him to seek the help of Bishop Sylvester who is in hiding. In the 15th century this document was exposed as one of the great forgeries of the Middle Ages. It probably dates from the 8th century, but it was often cited in the conflicts between the papacy and the secular powers of the 11th and 12th centuries.