The Donation of Constantine (Latin, Constitutum Donatio Constantini) is a fraudulent Roman imperial edict, supposedly issued by the Roman Emperor Constantine I in AD 324, which purported to grant Pope Sylvester I and his successors sovereignty and spiritual authority over Rome, Italy, and the entire Western Roman Empire.
The legend claims that the donation was Constantine's reward to Sylvester for curing him of leprosy by a miracle. Constantine moved the capital of the Roman Empire from Rome to Constantinople, which became the centre of power of the Eastern Roman Empire, later the Byzantine Empire. Were the document genuine, the popes would have ruled as emperors in the West; a succession of Western Emperors who were not popes after Constantine suggests that the document was false.
The Popes used the Donation to bolster their powers and their territorial claims as prince bishops in medieval Italy. The Italian humanist Lorenzo Valla proved that the Donation could not be genuine in 1440 by analysing its language, and showing that the Latin in the document could not have been written in the year 324. Currently it is thought that the document was written during the papacy of Stephen II, around 752, when the Roman Catholic Church needed something to bolster its authority against threats by secular powers.
See also: Vicarius Filii Dei