Pope Francis greets faithful after celebrating his first Palm Sunday Mass, in St. Peter's Square, at the Vatican, Sunday, March 24, 2013. Pope Francis celebrated his first Palm Sunday Mass in St. Peter's Square, encouraging people to be humble and young at heart, as tens of thousands joyfully waved olive branches and palm fronds. The square overflowed with some 250,000 pilgrims, tourists and Romans eager to join the new pope at the start of solemn Holy Week ceremonies, which lead up to Easter, Christianity's most important day (AP Photo/Andrew Medichini)