New York, USA - Pope Benedict XVI said farewell to the United States by celebrating an open-air Mass with 55,000 people at New York's Yankee baseball stadium.
Earlier, he visited Ground Zero in New York, the site of two of the 11 September 2001 attacks.
Well-wishers gave him a final cheer as he boarded a plane for Rome on Sunday.
The Pope's six-day tour, which has dominated the American media and attracted huge crowds, has been hailed as a great success by analysts.
Pope Benedict enjoyed a packed schedule during his visit, his first to the US since being elected head of the Catholic Church.
The trip coincided with the third anniversary of his election to the papacy and also his 81st birthday.
US Vice-President Dick Cheney hosted a farewell ceremony for the pontiff at New York's JFK airport, which was also attended by former President Bill Clinton and his wife, and presidential hopeful, Hillary Clinton.
Pope Benedict said "May God bless America!" before boarding the specially chartered Alitalia plane, nicknamed Shepherd One, for his flight back to Rome.
There was a party atmosphere at his final engagement at the Yankee stadium in New York, with clergy and lay members of the Church taking part in Mexican waves ahead of the pontiff's arrival.
Jazz musician Harry Connick Jr and gospel singer Kim Burrell performed prior to the Mass, and not for the first time, the Pope was greeted by a sea of people waving yellow and white handkerchiefs, the official papal colours.
'Feeling different'
The BBC's David Willey in New York said demand for the free tickets far outstripped supply.
Philip Giordano, 49, a tax lawyer from Connecticut, said: "I have never seen Yankee stadium so beautiful, and I have a season ticket."
His wife Suzanne added: "I am hoping to feel something. Everyone who has seen him (Pope Benedict) says they crumple. You come away just feeling different."
Earlier, at Ground Zero, Pope Benedict prayed for the rescuers and victims of the 11 September 2001 attacks, as well as "those whose hearts and minds are consumed with hatred".
He requested "eternal light and peace" for those who died, not only in New York but at the Pentagon in Washington DC and in Pennsylvania.
The Pope then met 24 people with links to the tragedy, taking the time to chat to each.
Unprecedented steps
During his visit, the Pope has been welcomed by huge crowds at the three Masses he has celebrated.
He has also not shied away from the difficult issues, taking the unprecedented step of repeatedly expressing regret for the scandal of sexual abuse carried out by Catholic clergy.
The Pope also hailed the growing influence of Hispanic migrants on the US Catholic church, and urged Americans to use their freedoms wisely.
He was given an unprecedented, personal welcome by US President George W Bush when he touched down at Andrews Air Force base on Tuesday.
He delivered a speech at the UN headquarters on Friday, and in a personal address on Saturday, Pope Benedict told 30,000 Catholic youths at a New York rally about growing up under the "monster" of Nazism.
With a candour that correspondents say has been a hallmark of this visit, he spoke publicly for the first time about being forced to join the Hitler Youth and being conscripted into the Nazi army.
Pope Benedict also visited a New York synagogue on Saturday, becoming the first leader of the Roman Catholic church to visit a Jewish place of worship in the US.