NEW YORK - Pope Benedict XVI celebrated his final Mass in the United States before a full house in storied Yankee Stadium on Sunday, blessing his enormous U.S. flock and telling Americans to use their freedoms wisely.

Benedict beamed at a joyous crowd of 57,000, hours after making a solemn stop to pray at the site of the Sept. 11, 2001, terrorist attacks on the World Trade Center.

He called the Mass "a summons to move forward with firm resolve to use wisely the blessings of freedom, in order to build a future of hope for coming generations."

And he repeated a core message of his six-day pilgrimage — that faith must play a role in public life, citing the need to oppose abortion.

The unwavering truth of the Roman Catholic message, he said, guarantees respect for the dignity of all "including the most defenseless of all human beings, the unborn child in the mother's womb." The crowd applauded the line.

Worshippers filled the seats, chanting, clapping and waving white and yellow handkerchiefs in the Vatican's colors as the white popemobile pulled in. At the end of the service, the German-born Benedict again processed out slowly as the strains of Beethoven's "Ode to Joy" serenaded him.

Outside the stadium, two yellow dump trucks filled with sand blockaded 161st Street before Mass, an extra level of security along with the heavy police presence. Pilgrims without tickets pushed up against metal police barricades, hoping to get a glimpse of the arriving pope.

Inside, ad-splashed outfield walls were draped in white with purple and yellow bunting. A white altar perched over second base, and the papal seal covered the pitcher's mound, suspended by white and yellow ribbons.

"I have never seen Yankee Stadium so beautiful, and I have season's tickets," said Philip Giordano, 49, a tax attorney from Greenwich, Conn., who won seats in the loge section behind home plate through a parish lottery. "It sure beats sitting in my local church."

Added his wife, Suzanne: "I'm hoping to feel something from (Benedict). Everyone who has seen him says they crumple, their knees buckle. You come away just feeling different."

The New Orleans crooner Harry Connick Jr., on the pre-Mass concert program, remarked that he is often asked if he's a practicing Catholic.

"Practicing?" he said. "I'm playing for the pope today."

Benedict seemed to enjoy his long procession to the altar in the popemobile, waving to people in the stands. From the altar, he stood to acknowledge the crowd's roar when New York Cardinal Edward Egan welcomed him.

He also praised the U.S. church, which has 65 million members, in his homily, saying that "in this land of freedom and opportunity, the church has united a widely diverse flock" and contributed greatly to American society.

Earlier, on a chilly, gray morning, the pope blessed the site of the terror attacks and pleaded with God to bring "peace to our violent world."

The visit by Benedict to ground zero was a poignant moment in a trip marked by unexpectedly festive crowds such as the one at Sunday's Mass.

Benedict was driven in the popemobile part-way down a ramp now used mostly by construction trucks to a spot by the north tower's footprint. He walked the final steps, knelt in silent prayer, then rose to light a memorial candle.

Addressing a group that included survivors, clergy and public officials, he acknowledged the many faiths of the victims at the "scene of incredible violence and pain."

The pope also prayed for "those who suffered death, injury and loss" in the attacks at the Pentagon and in the crash of United Airlines Flight 93 in Shanksville, Pa. More than 2,900 people were killed in the four crashes of the airliners hijacked by al-Qaida.

"God of peace, bring your peace to our violent world," the pope prayed. "Turn to your way of love those whose hearts and minds are consumed with hatred."

Benedict invited 24 people with ties to ground zero to join him: survivors, relatives of victims and four rescue workers. He greeted each member of the group individually as a string quartet played in the background. In his prayer, he also remembered those who, "because of their presence here that day, suffer from injuries and illness."

New York deputy fire chief James Riches, father of a fallen Sept. 11 firefighter, said the pope's visit gave him consolation.

"We said 'Where was God?' on 9/11, but he's come back here today and they've restored our faith," Riches said.

The site where the World Trade Center was destroyed is normally filled with hundreds of workers building a 102-story skyscraper, a memorial and transit hub. It bears little resemblance to the debris-filled pit where crews toiled to remove twisted steel and victims' remains.

The remains of more than 1,100 people have never been identified.

Benedict was joined by Egan, along with Mayor Michael Bloomberg, New York Gov. David Paterson and New Jersey Gov. Jon Corzine. The land is owned and managed by the Port Authority of New York & New Jersey.

Benedict has addressed terrorism several times during his six-day visit.

In a private meeting with President Bush, the two leaders "touched on the need to confront terrorism with appropriate means that respect the human person and his or her rights," according to a joint U.S.-Holy See statement.

Addressing the United Nations on Friday, Benedict said the way to peace was by ensuring respect for human dignity.

"The promotion of human rights remains the most effective strategy for eliminating inequalities between countries and social groups, and increasing security," the pope said.

Those whose rights are trampled, he said, "become easy prey to the call to violence and they then become violators of peace."

(Source: By Victor Simpson, Associated Press)