Vatican City - Sunday, Pope Francis marked several "firsts" in his career.
He led his first Sunday mass at the Vatican as pontiff, welcoming a crowd of nearly 300,000 to St. Peter's Square.
He surprised many by getting out of his car and mingling with parishioners.
He also sent out his first official tweet saying "Dear friends, I thank you from my heart and ask you to pray for me."
Pope Francis will be formally installed as the 266th pontiff of the Roman Catholic Church on Tuesday.