CASTEL GANDOLFO, Italy: Benedict XVI became the first pope in 600 years to resign Thursday, ending an eight-year pontificate shaped by struggles to move the church past sex abuse scandals and to reawaken Christianity in an indifferent world.

As bells tolled, the Swiss Guards standing at attention in Castel Gandolfo shut the doors of the palazzo shortly after 8 p.m. Thursday, symbolically closing out a papacy whose legacy will be most marked by the way it ended – a resignation instead of a death.

In a changing of the guard, the Swiss Guards in their yellow-and-blue striped uniforms handed over responsibility of protecting the 85-year-old Benedict to Vatican police as some of the faithful outside shouted “Viva il papa!” – Long live the pope!

The pope’s journey into retirement began with an emotional send-off from the Vatican, with Swiss Guards in full regalia and prelates kneeling to kiss Benedict’s papal ring one last time. Benedict’s closest aide wept by his side as they took their final walk down the marbled halls of the Apostolic Palace.

As bells tolled in St. Peter’s and in church towers across Rome, Benedict flew by helicopter to the papal vacation retreat in Castel Gandolfo in the hills south of Rome, where he will spend the first two months of his retirement.

Benedict leaves behind a church in crisis, still coping with the fallout of the sex abuse scandals, a central Vatican administration torn by divisions, and what Benedict said was a crisis of faith, with baptized Catholics in places of ancient Christian tradition thinking they can do without God.

In his final public remarks as pope, Benedict pledged to continue working for the good of the church in his retirement. Arms raised, he told a packed piazza from the palace balcony that as of his retirement, “I am simply a pilgrim beginning the last leg of his pilgrimage on this Earth.”

Benedict also reached out to the wider world electronically, sending a final tweet from his Twitter account, @Pontifex: “Thank you for your love and support. May you always experience the joy that comes from putting Christ at the center of your lives.” The day began with Benedict’s final audience with his cardinals, where he pledged his “unconditional reverence and obedience” to his successor, a poignant and powerful message that was utterly unexpected.

Inside the Vatican’s frescoed Clementine Hall, the pope appeared to be trying to defuse concerns about his future role and the possible conflicts arising from the peculiar situation of having both a reigning pope and a retired one.

Benedict also gave a final set of instructions to the “princes” of the church who will elect his successor, urging them to be united as they huddle to choose the 266th leader of the world’s 1.2 billion Catholics.

“May the College of Cardinals work like an orchestra, where diversity – an expression of the universal church – always works toward a higher and harmonious agreement,” he said.

It was seen as a clear reference to the deep internal divisions that have come to the fore in recent months following the leaks of sensitive Vatican documents that exposed power struggles and allegations of corruption inside the Vatican.

The audience inside the Apostolic Palace was as unique as Benedict’s decision to quit, with the pope, wearing his crimson velvet cape and using a cane, bidding farewell to his closest advisers and the cardinals themselves bowing to kiss his fisherman’s ring for the last time.

Some seemed to choke up at that moment, and a few lingered on to chat with the pope for as long as they could. But the scene seemed otherwise almost normal, with cardinals chatting on the sidelines waiting their turn to say goodbye.

Benedict said he would pray for the cardinals in coming days as they discuss the issues facing the church, the qualities needed in a new pope, and as they prepare to enter into the secret conclave to elect him.

Benedict’s decision to live at the Vatican in retirement, be called “emeritus pope” and “Your Holiness” and wear the white cassock associated with the papacy has deepened concerns about the shadow he might cast over the next papacy.

But Benedict has tried to address those worries over the past two weeks, saying that once retired he would be “hidden from the world” and living a life of prayer.

In his final speech in St. Peter’s Square Wednesday, he said he wasn’t returning to private life exactly, but rather to a new form of service to the church through prayer.

Thursday he went further, when he told the cardinals, “Among you is also the future pope, whom I today promise my unconditional reverence and obedience.”

The Vatican spokesman, the Rev. Federico Lombardi, said the pope’s pledge was in keeping with this effort to “explain how he intends to live this unprecedented situation of an emeritus pope.”

“He has no intention of interfering in the position or the decisions or the activity of his successor,” Lombardi said. “But as every member of the church, he says fully that he recognizes the authority of the supreme pastor of the church who will be elected to succeed him.”

The issue of papal obedience is important for Benedict. In his last legal document, he made new provisions for cardinals to make a formal, public pledge of obedience to the new pope at his installation Mass, in addition to the private one they traditionally make inside the Sistine Chapel immediately after he is elected.

Monday, the cardinals are expected to begin meeting to set the date for the conclave.