Pope Francis, the former Cardinal Jorge Mario Bergoglio, was formally installed as pope today. The Argentine pope was elected last week; today tens of thousands of people greeted him for his inaugural mass at the Vatican. The new pope delighted the crowds today by touring  St. Peter's Square for nearly half an hour in his open-air "popemobile." Rachel Donadio, the Rome bureau chief for our partner, The New York Times, has been reporting on Pope Francis's inauguration.