(This photo provided by the Italian Police Press office shows an aerial view of Saint Peter's Square prior to the start of the installation Mass of Pope Francis at the Vatican, Tuesday, March 19, 2013. Pope Francis has urged princes, presidents, sheikhs and thousands of ordinary people gathered for his installation Mass to protect God's creation, the weakest and the poorest of the world. (AP Photo/Matteo Losito, Italian Police HO))
