Pope Francis acknowledges the audience prior to speaking during a joint meeting of Congress in the House Chamber on Capitol Hill, in Washington DC, September 24, 2015. EPA/Drew Angerer

Pope Francis greets parishioners as he arrives for midday prayer at St. Matthew's Cathedral in Washington DC, September 23, 2015. Pope Francis is on a five-day trip to the USA, which includes stops in Washington DC, New York and Philadelphia, after a three-day stay in Cuba.  EPA/Drew Angerer