The following is the full account of this historic moment in the Church, according to the Vatican Information Service:
This afternoon, shortly after 5:00pm, Benedict XVI left the Vatican for the last time as Supreme Pontiff. A few moments earlier, in the San Damaso Courtyard of the Vatican Apostolic Palace, Cardinal Tarcisio Bertone, S.D.B., secretary of State of His Holiness, and other members of that dicastery bid him farewell. In full military regalia, the Swiss Guard troops paid him homage. Also present were Cardinal Agostino Vallini, vicar general of Rome, and Cardinal Angelo Comastri, vicar general of His Holiness for Vatican City. Many of the workers of the Vatican City State, with their families, were also in attendance and greeted the Pope with warm applause.
Before leaving the Vatican, Benedict XVI issued his last tweet: "Thank you for your love and support. May you always experience the joy that comes from putting Christ at the centre of your lives."
Shortly afterwards the Holy Father, accompanied by his private secretary, Archbishop Georg Ganswein, prefect of the Papal Household, took a car to the Vatican heliport where the dean of the College of Cardinals, Cardinal Angelo Sodano, greeted him and he boarded the helicopter that carried him to Castel Gandolfo. As the helicopter lifted off, the bells of St. Peter's Basilica and the churches of Roma began ringing.
The Pope's helicopter flew over the city of Rome, passing by the Colosseum and St. John Lateran Basilica, and landed at the Castel Gandolfo heliport just after 5:20pm. Awaiting the Holy Father were Cardinal Giuseppe Bertello and Bishop Giuseppe Sciacca, respectively president and secretary general of the Governorate of Vatican City State along with Saverio Petrillo, director of the Pontifical Villas, Bishop Marcello Semeraro of the Diocese of Albano, and civil and religious authorities of the area. The Pope was then taken by car to the Castel Gandolfo Apostolic Palace, where he was greeted by hundreds of people while the bells of Castel Gandolfo's parishes rang out.
Shortly afterwards, Benedict XVI appeared at the balcony of the Apostolic Palace and said to the many faithful who were waiting to thank him for his pontificate: “Thank you. Thank you all. Dear friends, I am happy to be with you, surrounded by the beauty of Creation and your well wishes, which do me such good. Thank you for your friendship and your affection. You know that this day is different for me than the preceding ones. I am no longer the Supreme Pontiff of the Catholic Church, or I will be until 8:00 this evening and then no longer. I am simply a pilgrim beginning the last leg of his pilgrimage on this earth. But I would still—with my heart, with my love, with my prayers, with my reflection, and with all my inner strength—like to work for the common good and the Good of the Church and of humanity. I feel very supported by your kindness. Let us go forward with the Lord for the good of the Church and the world. Thank you. I now wholeheartedly impart my blessing. Blessed be God Almighty, Father, Son, and Holy Spirit. Good night! Thank you all!”
Benedict XVI's pontificate concludes at 8:00pm this evening (Rome time), at which time the period of the Sede Vacante begins. The Swiss Guards will no longer be in charge of his safekeeping—which detail will then be undertaken by the Vatican Gendarmerie—and will return to the Vatican to offer their service to the College of Cardinals. During this period the twitter account @Pontifex will be deactivated. Once elected, the new Pope may, if he so desires, take over its use. Benedict XVI's Fisherman's Ring and the seal of his pontificate will also be destroyed at that time and the papal apartments in the Vatican Palace will be sealed.
