Leo XIV celebrated his first mass as pope on Friday, the day after becoming the first US head of the Catholic Church, with the world's eyes watching for signs of what kind of leader he will be.
Chicago-born Robert Francis Prevost on Thursday became the 267th pope, spiritual head of the world's 1.4 billion Catholics and successor to Argentina's Pope Francis, after a secret conclave by his fellow cardinals in the Vatican's Sistine Chapel.