Last week, Marc posted about the fantastic exhibit of the Vatican archives currently underway at the Capitoline Museum in Rome. One of the documents on display is Lorenzo Valla’s definitive refutation of the so-called “Donation of Constantine.” Forgotten today, except by historians of law and religion, the Donation played an important role in justifying papal assertions of temporal power in the Middle Ages.
The Donation was a purportedly an imperial decree, signed by the Emperor Constantine, granting the entirety of the Western Roman Empire to Pope Sylvester I and his successors. Constantine supposedly made this gift in 
gratitude for Sylvester’s actions in miraculously curing him of leprosy and baptizing him in the Christian faith. Throughout the Middle Ages, the Donation was taken as authentic, and it played a major role in justifying papal assertions during the investiture crisis that Harold Berman famously described in Law and Revolution. By the Renaissance, however, scholars within the Church had begun to have doubts. On the basis of textual analysis, Valla, a priest, demonstrated that the Donation was a forgery in the fifteenth century. Protestant reformers made much of the forgery in their arguments against the Catholic Church.
All this is fun for law-and-religion nerds, but, back when people believed it to be true, the Donation was the subject of some powerful art. On the Coelian Hill near the Colosseum, off a very quiet street, stands a medieval church called Santi Quattro Coronati. In the church’s courtyard, a separate entrance leads to the Oratory of St. Sylvester, where — after giving a small donation — you can see a series of medieval frescoes that tell the whole story: Constantine’s illness, his subjects’ despair, his miraculous cure by Pope Sylvester, and the Donation itself (above). In their credulity, the frescoes are really rather charming. It’s definitely worth going out of your way to see them — even if you’re not a law-and-religion nerd, and even if the story is a complete hoax.
Thanks for posting this. I would quibble, however, with your characterization of the Donation of Constantine as a “complete hoax”. In the Middle Ages, documents were often written (pre-dated?) to record what was believed to be the truth or custom. While we often refer to these documents as “forged”, they were not necessarily forged in the sense that we consider forgery — that is, the intentional fabrication of facts in a document. We have ways of analyzing and synthesizing evidence that were unavailable to people in the Middle Ages, so we often can tell that a charter giving a parcel of land to someone that was supposed to be from the sixth century was in fact written in the twelfth — but that does not necessarily mean that the person who had the charter inscribed knew that the land had never been given and had forged a document for fraudulent purposes. The charter could have been written to record what people at the time believed to be the history of that parcel of land. (c.f., M.T. Clanchy’s “From Memory to Written Record”).