The privileged altar of Saint Gregory the Great, in the church of Saint Gregory on Monte Crelio in Rome. It is related that Saint Gregory, by saying one Mass, liberated the soul of a monk, named Justus, from Purgatory; so the faithful have confidently hoped that any Mass on this altar would free a soul from Purgatory. The Congregation of Indulgences approved this confidence. The indulgence of the Gregorian altar is no longer granted to other altars.