Pope Begins Holy Week With Impromptu Homily

Pope Francis greets young people after leading Palm Sunday mass, at St Peter's Square in the Vatican April 13, 2014.

Pope Francis inaugurated Holy Week, which culminates with Easter, by celebrating Palm Sunday Mass with pilgrims in St. Peter's Square on Sunday.

The pontiff ignored his prepared homily and spoke entirely off-the-cuff in a remarkable departure from practice. Later, he hopped off his pope mobile to pose for "selfies'' (self-snapped) photographs with young people in the crowd.

Francis called on people, himself included, to look into their own hearts to see how they are living their lives.

In a crowd of around 100,000 locals, pilgrims and tourists, people clutched olive tree branches, tall palm fronds or tiny braided palm leaves shaped like crosses that were blessed by Francis at the start of the ceremony.

For Christians, Palm Sunday commemorates Jesus' triumphant entry into Jerusalem, when palm branches were strewn in front of him. Later, according to the Holy Scriptures, he would be arrested and crucified.