Present at Mass were some 140 official delegations including Croatia's delegation led by Sabor Speaker Vladimir Seks. After the religious service the pope, former German Cardinal Joseph Ratzinger, received state delegations in the Basilica, and first of them was the German and then Italian delegation.
The inaugural ceremony began with Benedict XVI's visit to the grave of Pope John Paul II in St Peter's Basilica.
During his homily which he delivered in Italian, Pope Benedict XVI repeated messages of his predecessor urging the faithful to open the door for Jesus Christ.
"My real programme of governance is not to do my own will, not to pursue my own ideas, but to listen, together with the whole Church, to the word and the will of the Lord," the 265th pontiff of the Roman Catholic Church said during the open-air mass. He called for unity among Christians and pointed out poverty and hunger as main problems of the contemporary world.