Pope Francis prays in front of the Marian icon “Salus Populi Romani” at the Basilica of St. Mary Major in Rome March 15. According to legend, late in the 6th century Pope Gregory I had the icon carried through the streets of Rome in prayer that the Black Plague would end, and in 1837, Pope Gregory XVI prayed before the image for an end to a devastating cholera outbreak. (Vatican Media)