In 1263 or 1264, a young priest visiting from Prague on his way to Rome was saying Mass when he was amazed to see the host and wine actually turn into the body and blood of Christ. This then spilled onto the white altar cloth creating a stain resembling Jesus, onto the marble floor (a piece of it now in the reliquary – see photo), and into the catacombs below.
The event had such a tremendous impact on the Christian world that Pope Urban IV, who was in nearby Orvieto at the time, immediately called it a miracle and inaugurated the Feast of Corpus Domini, which is still celebrated throughout the Catholic world today.
