Short answer. Yes, and this is not a fringe claim. The Donation of Constantine (Latin Constitutum Constantini) is one of the most consequential forgeries in European history: a document that pretends to be Emperor Constantine the Great handing the pope sovereignty over Rome and the Western Empire, but which was actually fabricated some four hundred years after Constantine died. The Renaissance scholar Lorenzo Valla proved it a forgery in 1440 by analyzing its language. And the Catholic Encyclopedia itself, in its 1913 entry, calls the document "without doubt a forgery, fabricated somewhere between the years 750 and 850." The remarkable part is not that it was faked. It is that a fake ran the political map of Europe for seven centuries first.
What the document claimed
The Constitutum Constantini tells a tidy miracle story with an enormous legal payload. In it, the Emperor Constantine, cured of leprosy through baptism by Pope Sylvester I (reigned 314-335), repays the favor by granting the papacy almost everything. Sylvester and his successors are given primacy over the other great patriarchal sees (Antioch, Alexandria, Constantinople, Jerusalem), the right to wear imperial insignia and regalia, and, decisively, temporal dominion over Rome, all of Italy, and the provinces of the Western Empire. Constantine, the text says, withdrew to the East precisely so the pope could rule the West. In a single parchment, spiritual authority is fused with imperial sovereignty and the papacy is handed a legal deed to a kingdom. That deed, had it been genuine, would have made the pope the rightful secular ruler of the West by the personal act of the first Christian emperor.
Why it cannot be genuine
The forgery is betrayed by its own language, which is exactly how Valla caught it. A document supposedly drafted in Constantine's fourth-century Roman chancery is written instead in the crude, later Latin of the eighth century, full of words and constructions no fourth-century Roman scribe would use. It refers to Constantinople as an established patriarchal see, though at the dramatic date of the grant that city did not yet hold that rank (and had barely been refounded). It uses terms like satrap that make no sense in an imperial Roman decree. It speaks of realities that simply did not exist in Constantine's lifetime. Modern scholarship, following the *Catholic Encyclopedia*'s own dating, places its composition between roughly 750 and 850, most likely in the orbit of the Roman Lateran during the papacy's alliance with the Frankish kings, precisely when the popes were assembling the legal case for the newly forming Papal States. The document is a period piece of the eighth century wearing a fourth-century mask.
How a fake ran the map for seven centuries
A forgery is only as powerful as the number of people who cite it in earnest, and this one was cited by nearly everyone. From at least the eleventh century, popes and canon lawyers invoked the Donation to justify papal temporal power and territorial claims against emperors and kings. It was folded into the medieval collections of canon law, which gave it the force of settled precedent. It underwrote the very idea of the Papal States, the swath of central Italy the popes ruled as sovereigns into the nineteenth century. Its influence was so notorious that Dante, writing around 1320, blamed it directly for corrupting the Church, crying out in the Inferno (Canto 19), "Ah, Constantine, of how much ill was cause, not thy conversion, but those rich domains that the first wealthy Father took from thee." For medieval Europe, a document written by an eighth-century forger functioned as the founding charter of papal statehood.
The unmasking (1440)
The demolition came from a humanist with a grudge and a method. Lorenzo Valla, a brilliant and combative philologist then employed by King Alfonso of Aragon (himself locked in a territorial fight with the pope), wrote De falso credita et ementita Constantini donatione declamatio, "Discourse on the Forgery of the Alleged Donation of Constantine," in 1440. Valla did not argue from theology or politics. He argued from the text: the Latin was wrong for the period, the vocabulary anachronistic, the historical references impossible, the whole thing riddled with tells a fourth-century imperial document could not contain. He was not entirely first (the German cardinal Nicholas of Cusa had already questioned it in 1433, and the chancery of Emperor Otto III had denounced it as a forgery around the year 1001), but Valla's dissection was so thorough that it became a landmark in the birth of modern textual criticism. Later reformers seized on it: Ulrich von Hutten printed Valla's treatise in 1517, and it became a weapon in the Reformation's case against Rome. The method Valla pioneered, reading a document's language to date it, is now simply how historians work.
The honest part
Keep the tiers straight, because the sober version is the strong one. What is bedrock and conceded by all sides, including the Church's own reference works, is that the Donation is a forgery composed long after Constantine. What remains genuinely contested among historians is the finer detail: exactly who wrote it, precisely when within that 750-850 window, and for which immediate purpose (buttressing the Frankish alliance, resisting Byzantine claims, or internal Roman politics). The point of recovering this is not that the medieval papacy was uniquely dishonest; forgery was distressingly common in an age with no archives and high stakes. The point is narrower and sharper: one of the load-bearing legal claims to the pope's temporal sovereignty rested, provably, on a document that nobody in Constantine's century ever wrote, and it took the tools of honest reading, not faith and not force, to say so out loud.
Common questions
Is the Donation of Constantine real?
No. It is a forgery. The document presents itself as a fourth-century grant from Emperor Constantine to Pope Sylvester I, but it was actually written roughly four centuries later, between about 750 and 850. Lorenzo Valla proved this in 1440, and the Catholic Encyclopedia itself describes it as "without doubt a forgery."
What did the Donation of Constantine claim?
It claimed that Constantine, after being baptized and cured of leprosy by Pope Sylvester I, granted the papacy primacy over the other patriarchates, the right to imperial insignia, and temporal sovereignty over Rome, Italy, and the Western Empire. In effect it purported to transfer secular rule of the West to the pope by the emperor's own hand.
Who proved the Donation of Constantine was a forgery?
The Italian humanist Lorenzo Valla, in his 1440 treatise De falso credita et ementita Constantini donatione declamatio. He showed on linguistic and historical grounds that the document's Latin and content belonged to a much later era than Constantine's. Nicholas of Cusa had already raised doubts in 1433, and imperial officials as early as around 1001.
When was the Donation of Constantine written?
Between roughly 750 and 850, in the eighth or early ninth century, most likely in Rome during the papacy's alliance with the Frankish kings and the formation of the Papal States. That is about four hundred years after the death of Constantine in 337.
Does the Catholic Church admit the Donation is a forgery?
Yes. Mainstream Catholic scholarship has long acknowledged it. The 1913 Catholic Encyclopedia entry states plainly that the document is "without doubt a forgery, fabricated somewhere between the years 750 and 850." Its authenticity has not been seriously defended by historians for centuries.
Why did the Donation of Constantine matter?
Because it was believed. From the eleventh century onward it was cited to justify the pope's temporal power and territorial claims, was written into canon law, and underwrote the Papal States that popes ruled into the nineteenth century. A forged document functioned for seven hundred years as a founding charter of papal statehood.
This page settles a provenance, not a piety. The papacy's spiritual claims stand or fall on their own ground; what falls here is one specific legal deed, exposed by reading its own words. The oldest tool against a forged authority turns out to be the plainest one: check when the document could actually have been written.
Sources
the Constitutum Constantini (Donatio Constantini), text of the forged grant. Lorenzo Valla, De falso credita et ementita Constantini donatione declamatio (1440; English: Christopher B. Coleman, The Treatise of Lorenzo Valla on the Donation of Constantine, 1922). Catholic Encyclopedia (1913), "Donation of Constantine" ("without doubt a forgery, fabricated somewhere between the years 750 and 850"). Encyclopaedia Britannica, "Donation of Constantine." Dante Alighieri, Inferno, Canto 19. Nicholas of Cusa, De concordantia catholica (1433); Emperor Otto III's denunciation, c. 1001; Ulrich von Hutten's 1517 printing of Valla.