"Under St. Peter's" is a short story by Harry Turtledove, first published in The Secret History of Vampires, edited by Darrell Schweitzer, DAW, 2007. It was reprinted in By Blood We Live, edited by John Joseph Adams, Night Shade Books, 2009, and We Install and Other Stories, 2015. In the We Install collection, Turtledove says that this is his rare concession to "secret history", a genre which he is usually uninterested in writing.