VATICAN CITY, Feb. 27, 2013— -- On his final full day as the leader of the Roman Catholic Church, Pope Benedict XVI thanked a huge crowd for respecting his historic decision to step down and told them that God will continue to guide the church.
"The decision I have made, after much prayer, is the fruit of a serene trust in God's will and a deep love of Christ's Church," Benedict said to cheers in his last public words as pope.
Benedict, 85, is the first pope to resign in 600 years. He told the crowd today that he was "deeply grateful for the understanding, support and prayers of so many of you, not only here in Rome, but also throughout the world."
Under sunny skies on this late February day, hundreds of thousands of people, some waving flags, some banners, flocked to Vatican City to see Benedict make a final lap around St. Peter's Square. Throughout his eight-year papacy, Benedict has conducted a weekly audience from St. Peter's. Before delivering his last papal address today, Benedict waved to the festive group of supporters as he toured the square in his glass-encased popemobile.
The city of Rome planned for more than 200,000 people to head to the Vatican for today's event. Streets around St. Peter's were blocked off to cars as pedestrians from around the world headed to the square.
Among them were Rachael Richter and some classmates from Pittsburgh's Duquesne University who are studying abroad.
"When I came here, I never expected that something like this would happen," she said. "It's the opportunity of a lifetime, so I'm just taking it all in and enjoying every minute of it."
But it was also bittersweet, judging by the reactions from observers like Christopher Kerzich, who hails from Chicago and is studying at the Pontifical North American College in Rome.
"It's definitely a historic moment," he said. "There's a sadness of Pope Benedict not being there to shepherd our church but a sense of excitement, too."
Kerzich added: "Looking around the crowd I saw people with faces of sadness. But then when the Holy Father came out, there was this great joy that came across the people. So I think it's mixed emotions.
"Many Catholics have come to love this pontiff, this very humble man. He is a man who's really fought this and prayed this through and has peace in his heart. I take comfort in that and I think a lot of Catholics should take comfort in that."
Either way, the conclave to elect Benedict's replacement will start next month at a date yet to be determined. Benedict issued a decree known as a "motu poprio" that will allow cardinals to convene the conclave sooner than the March 15 date that would have been mandated under the old rules.
Benedict today asked the faithful to pray for him and for the new pope.
"My heart is filled with thanksgiving to God who ever watches over his church," Benedict said.
The German-born Benedict, who had appeared frail at times in recent months, seemed more energized in his remarks today. He has said he will devote more time to prayer and meditation after he leaves the papacy.
Benedict will meet Thursday with his cardinals in the morning and then flies by helicopter at 5 p.m. to Castel Gandolfo, the papal residence south of Rome. Benedict will greet parishioners there from the palazzo's balcony, his final public act as pope.
Then, at 8 p.m., the exact time at which his retirement becomes official, the Swiss Guards standing outside the doors of the palazzo at Castel Gandolfo will go off duty, their service protecting the head of the Catholic Church finished.
In retirement, Benedict will continue to wear white and will be called "Pope Emeritus," or the "Supreme Roman Pontiff Emeritus" or "Your Holiness," the Vatican announced Tuesday. Benedict will ditch his trademark red shoes, opting for a pair of brown shoes given to him on a trip to Mexico. But he will still reside on Vatican grounds in a former nunnery.
Benedict's final days as pope have been marked by controversy. For nearly a week now Italian newspapers speculated that Benedict really resigned because of a dossier he was given detailing a sex and blackmail scandal in the Catholic Church. The Italian media news reports do not state any attribution.
It turns out a dossier does exist. The Vatican spokesman Monday underscored that the contents of the dossier are known only to the pope and his investigators, three elderly prelates whom the Italian papers have nicknamed "the 007 cardinals."
But the dossier itself will remain "For the Pope's Eyes Only."
Also Monday, Britain's top cardinal, Keith O'Brien, resigned and decided not to participate in the upcoming papal election following published reports in a British newspaper that he made unwanted sexual advances toward four priests in Scotland in the 1980s.
He has denied the allegations.
The Scottish cardinal, 74, is the latest voting member of the College of Cardinals to be tainted by scandal.
U.S. Cardinal Roger Mahony has also faced pressure to bow out of the conclave on the grounds that their moral authority has been compromised because of the church sex-abuse scandal. Church documents show that for more than a decade he enabled priests to keep molesting children rather than report them to law enforcement.
Documents from the Archdiocese of Los Angeles show that Mahoney covered up for pedophile priests.
Mahony is already in Rome and has been blogging about the upcoming conclave and lashing out at his critics for persecuting him.
Pope Benedict issued new rules about the timing and procedures of the vote to choose his successor.
Benedict has already given the College of Cardinals the go-ahead to move up the start date of the conclave, tossing out the traditional 15-day waiting period. But the cardinals won't be able to set a date until their official meetings begin Monday.
The Associated Press contributed to this report.