Pope Francis celebrates Mass, sits in back row

Pope Francis celebrated Mass Friday morning for the Vatican's gardeners and house cleaners, apparently after walking into the celebration unexpectedly and joining the group by quietly sitting among the congregation.

L'Osservatore Romano, the Vatican's semi-official newspaper, has a brief account of the Mass, showing a picture of a Francis sitting in the third row of seating.

According to the newspaper, the Mass was taking place in the chapel of the Domus Sanctae Marthae, the Vatican hotel where Francis has been staying since the conclave that elected him pontiff. Although the Vatican's apostolic palace, where popes have lived for centuries, is apparently ready, Francis has yet to move into that facility, instead preferring to stay in the hotel, at least for now.

During a short homily, L'Osservatore Romano reports, Francis told the small group not to have hearts of stone.