Eric J. Lyman, Special for USA TODAY
VATICAN CITY - Pope Francis was officially inaugurated as the 266th occupant of the Throne of St. Peter Tuesday in front of the biggest crowd yet to see the new pope, who was elected six days ago.
Crowds spilled out of St. Peter's Square onto neighboring streets as Italian police said they were bracing for as many as 1 million people to descend on St. Peter's Square to watch the Mass that marked the official start of the papacy of the former Argentine Cardinal Jorge Mario Bergoglio.
In his homily, Pope Francis implored the faithful to "never forget that authentic power is service, and that the Pope too, when exercising power, must enter ever more fully into that service." He said that today, amid so much darkness, we need to see the light of hope.
Ahead of the Mass, the pope made his way around St. Peter's Square in his open-air popemobile. He stopped frequently to greet the faithful, mixing informally with the crowd and shaking the hands of the assembled. Then, as the ceremony got under way and Pope Francis emerged toward the alter at St. Peter's Basilica, the crowd fell silent.
"What a treat to be here for this," said John Silver, a municipal employee from Leicester, United Kingdom. "When we discovered the Mass was today we were in Florence, but we came to be part of it. He (the pope) is a wonderful man."
Among the more than 130 national delegations attending the Mass were U.S. Vice President Joe Biden, and at least 31 heads of state, including Italian Prime Minister Mario Monti, and Cristina Fernandez de Kirchner, president of the pope's native Argentina.
On Monday, Fernandez de Kirchner became the first foreign head of state to be received by the new pope. The two have had a sometimes prickly relationship in the past. For many observers it was a recollection of the former cardinal's alleged role in Argentina's so-called "Dirty War" between 1976 and 1983, where he is said to have failed to protect Jesuit priests working in the slums of Buenos Aires. Also on Monday, Fernandez de Kirchner asked Francis to help mediate the 30-year dispute over the Falkland Islands. Argentina lost a brief war against the U.K. in 1982 over the fate of the South Atlantic islands.
Maria Susana Saugar, 77, from Buenos Aires, who has a daughter studying in Bologna but came to Rome for today's inauguration, said: "It's a pride for Argentina, but also for the church. I think he will change the church, return it to its humble roots as a ministry to people in need. I love him and what he stands for. I agree with his views."
Also on hand are delegations from 33 Christian churches, 16 Jewish delegations, along with delegations representing Muslims, Buddhists, and Sikhs.
By some estimates, this could be the largest crowd in St. Peter's Square since the funeral of Pope John Paul II in 2005.
One dignitary who will not be at the ceremony is former Pope Benedict XVI, who last month become the first pope in nearly six centuries to abdicate. Now pontiff emeritus, Benedict has moved to Castel Gandolfo, south of Rome, and has kept a distance from the Holy See since stepping down Feb. 28.
Tuesday will mark the official unveiling of the pope's coat of arms -- unchanged from the one he used as bishop and cardinal, though it will now include the crossed keys that represent the papacy. (His motto: "miserando atque eligendo" -- latin for "because he saw him through the eyes of mercy and chose him.") Francis will receive his papal ring, made of silver and gold and called The Fisherman's Ring in honor of the first pope, St. Peter, who was a fisherman.
Domenico Polimeni, 63, a retired worker from the Italian ministry of labor who is from Calabria but lives in Rome, said: "It's a huge emotion to be here to see the church in transformation. He (Pope Francis) has a direct style, pastoral, he spent his life with poor people, for him it's a natural."
Additional coverage is available in our "Electing the Pope" section.