Donatio Constantini and Constitutum Constantini, the best-known and most important forgery of the Middle Ages, the document purporting to record the Roman emperor Constantine the Great’s bestowal of vast territory and spiritual and temporal power on Pope Sylvester I (reigned 314–335) and his successors. Based on legends that date back to the 5th century, the Donation was composed by an unknown writer in the 8th century. Although it had only limited impact at the time of its compilation, it had great influence on political and religious affairs in medieval Europe until it was clearly demonstrated to be a forgery by Lorenzo Valla in the 15th century.