Actually, you guys might want to consider the documentation backing up the claim that Constantine did do this.
Here it is
Donation of Constantine
(Lat.,
Donatio Constantini).
Manuscript (Bibliothèque Nationale, Paris, MS. Latin 2777)
And it bears the title: “Constitutum domni Constantini imperatoris”. It is addressed by Constantine to Pope Sylvester I (314-35) and consists of two parts. In the first (entitled “Confessio”) the emperor relates ….
In the second part (the “Donatio”) Constantine is made to confer on Sylvester and his successors the following privileges and possessions: the pope, as successor of St. Peter, has the primacy over the four Patriarchs of Antioch, Alexandria, Constantinople, and Jerusalem, also over all the bishops in the world. …
Okay, okay, there is one tiny weeny little problem with it. It was proved to have been written hundreds of years after the Emperor Constantine died.
Code:
Here is a 15th Century manuscript proving that this document to be a forgery. . Lorenzo Valla shows that the text could not have been written in the fourth century, the age of Constantine the Great, by revealing many anachronisms in form and content. It is an eighth-century forgery
loc.gov/exhibits/vatican/arch.html#obj17
**The Donation of Constantine **An excerpt from the book “The Building of Christendom”, from pgs. 294-295, Volume Two from the “History of Christendom” series by Dr. Warren Carroll
Code:
The Donation of Constantine, whose oldest manuscript cannot be surely dated before 800, purports to be a grant of quasi-imperial powers over Rome, Italy, "and all the Western regions" to silent Pope Silvester I from Constantine, whom Silvester is said to have baptized, as he went east to establish his new capital in Constantinople. That this document could not be authentic became patently obvious at the very dawn of critical historical scholarship in the Renaissance.
It was the outgrowth of a long-developed legend, the most successful of a number of efforts to fill a myth the extraordinary historical void which Silvester’s pontificate in the vitals years 314-335 presents to Christian posterity. Among the kernels of historical fact at the roots of this legend were Constantine’s grant to the church in Rome of the Lateran palace and various other buildings and benefits, during the years immediately after his conversion and the capture of Rome.
While it seems from a letter of Pope Hadrian I (772-795) to Charlemagne that Pope Hadrian was familiar with the legend, no document of Pepin’s or Charlemagne’s time specifically cites the forged donation. When it finally appears, it is in Frankish sources. No Pope officially cited it until 1054. If the Donation of Constantine was forged for Pepin and used to mislead him, no word or act of his reflects it. Neither he nor Popes Stephen III or Paul I ever claimed all of Italy for the Papacy, nor referred to Constantine or any other Roman emperors as the source of their claims.
The repeated references in the letters and documents of Pope Stephen III to demands for the return of cities from the Lombards do not by any means necessarily imply some secret reading of the Donation of Constantine. They are simply and reasonably explained and reflecting the well-founded conviction that the Lombards had no right to seize them, and should return them to the inhabitants from whom they had been taken - but not to Byzantine rule, since no Pope could have seriously considered initiating the delivery of Italian territory with its Catholic people to an iconoclast emperor who had just declared himself the equal of the apostles.
Additional resources:
Donation of Constantine - Catholic Encyclopedia