Pope Benedict XVI has left the Vatican on his final day as Pope, saying he "will simply be a pilgrim" starting his last journey on earth.
The 85-year-old pontiff was flown by helicopter to the papal retreat at Castel Gandolfo, near Rome.
At 20:00 local time (19:00 GMT) he will officially cease to be the Pope.
His deputy, Cardinal Tarcisio Bertone, will be in charge of the world's 1.2 billion Roman Catholics until a new pope is elected next month.
Earlier, Benedict met his cardinals, vowing "unconditional obedience and reverence" to his eventual successor.
He is the first pontiff in 600 years to step down.
Church bells rang across the Vatican as Benedict boarded the helicopter shortly after 16:00.
Before that, applause rippled as the pontiff was greeted for the last time by top officials in the Curia - the administrative body that runs the Holy See.
The Pope landed at Castel Gandolfo, 15 miles (24km) south-east of the Italian capital, about 15 minutes later.
He then appeared at a window overlooking the public square in Castel Gandolfo to bless a cheering crowd.
"Thank you very much for your friendship," Benedict said.
"As of 20:00 (19:00 GMT) I'll no longer be a pontiff. I will simply be a pilgrim who is starting the last phase of his pilgrimage on this earth."
"Let's go forward with God for the good of the Church and the world."
In his final tweet, Benedict wrote: "Thank you for your love and support. May you always experience the joy that comes from putting Christ at the centre of your lives."
Benedict's formal resignation as Pope will be marked when the Swiss Guards at the gate of Castel Gandolfo march off for their return to the Vatican.
The German pontiff, who was born Joseph Ratzinger, will continue to be known as Benedict XVI, with the new title of "pope emeritus".
In his retirement, he will wear a simple white cassock rather than his papal clothes and swap his famous red shoes - the colour is symbolic of the blood of the early Christian martyrs - for brown.
His "Fisherman's Ring", the special signet ring which contains the Pope's name and is impressed to validate certain official documents, is expected to be destroyed along with the lead seal of the pontificate.
The long-time theologian is expected eventually to retire to a monastery on a hill inside Vatican City, with officials saying he will not be able intervene publicly in the papacy of his successor, though he may offer advice.
His successor must focus on reforming the Vatican bureaucracy, which has often been overly hesitant to react to the various crises which have arisen during Benedict's papacy, the BBC's David Willey reports from the Vatican.
Beset by scandals
Earlier on Thursday, the Pope received the cardinals at the Vatican's Clementine Hall, warmly embracing Cardinal Angelo Sodano, who passed on best wishes on behalf of those gathered.
"Among you there is also the future pope to whom I promise my unconditional obedience and reverence," the pontiff said.
"The Church is a living being," he added, but it "also remains always the same".
In his public farewell speech on Wednesday, Benedict hinted at Vatican infighting.
His decision to resign has been openly criticised by Australia's top Catholic, Cardinal George Pell, who questioned his leadership skills.
The Church has been beset by scandals over sexual abuse by priests and leaked confidential documents revealing internal corruption and feuding.
An estimated 150,000 people packed into St Peter's Square on Wednesday to hear Benedict, resigning after seven years in office.