Pope Francis arrives for Sunday Mass on the Benjamin Franklin Parkway in Philadelphia, Pa., Sept. 27, 2015.
Pope Francis arrives for Sunday Mass on the Benjamin Franklin Parkway in Philadelphia, Pa., Sept. 27, 2015.

PHILADELPHIA, PENNSYLVANIA - Pope Francis celebrated a late-afternoon Sunday Mass before hundreds of thousands in Philadelphia, capping off a frenetic, six-day visit to the United States that mesmerized Americans and energized his followers.

People gather on the Benjamin Franklin Parkway bef
People gather on the Benjamin Franklin Parkway before the Papal Mass in Philadelphia on Sunday, Sept. 27, 2015.

As crowds filled the sprawling, leafy Benjamin Franklin Parkway in central Philadelphia, the pope said their mere coming together for the ritual was "a kind of miracle in today’s world."

"And how beautiful it would be if everywhere, even beyond our borders, we could appreciate and encourage this prophecy and this miracle!" the Argentine native said in his homily, speaking in Spanish.

Wearing the green vestment of the liturgical season, Francis sat on a purpose-built stage. With the Philadelphia Art Museum behind him, Francis could see over the nearly 1.6 kilometer-long river of humanity to the statue of William Penn, founder of Pennsylvania, atop City Hall.  

The official reason for his visit was to attend the World Meeting of Families, held in the United States for the first time. And in his homily, Francis spoke about family life, saying faith is lived out in the details.

"They are little signs of tenderness, affection and compassion. Like the warm supper we look forward to at night, the early lunch awaiting someone who gets up early to go to work,” he said. "Faith grows when it is lived and shaped by love. That is why our families, our homes, are true domestic churches."

On arrival, the pope’s heavily guarded motorcade looped around the parkway, which Philadelphians like to compare to Paris' Champs-Elysees. He took his time, kissing babies and waving to the adoring throngs.

An unidentified child, carried from the crowd, tou
An unidentified child, carried from the crowd, touches Pope Francis' face as he heads to celebrate Sunday Mass on the Benjamin Franklin Parkway in Philadelphia, Sept. 27, 2015.

The pope also exhorted followers to bridge differences. "May our children find in us models of communion, not division," he said.

Francis' focus on children linked to his declaration that morning that the Roman Catholic Church would work "zealously" to prevent and atone for priests’ sexual abuse of youngsters and for superiors’ efforts to conceal grave misdeeds.

"I remain overwhelmed with shame that men entrusted with the tender care of children violated these little ones and caused grievous harm," said Francis, who'd met early Sunday morning with three women and two men who'd been victimized as youths. "I am profoundly sorry. God weeps."

Francis made those remarks to at least 300 bishops, gathered for a morning meeting at a chapel of St. Charles Borromeo Seminary.

After the Sunday Mass, the pope will have a private meeting with U.S. Vice President Joe Biden and his family, then board an flight back to Rome.

The Mass caps an intense week – in Washington, New York and Philadelphia – in which the leader of the world’s 1.2 billion Catholics has demonstrated his devotion to the poor and his determination to engage the powerful in helping them.

In Washington, Francis met with President Barack Obama and addressed the U.S. Congress, also visiting a homeless shelter. In New York, he addressed world leaders at the U.N. General Assembly and encouraged youngsters, including many immigrants, at an elementary school in East Harlem.

Sexual abuse

In Philadelphia, the pope made the church's most profound apology yet on the scandalous sexual abuse of children by clergy.

On Sunday morning, the pope listened to three women and two men who'd been abused as youngsters. He prayed with them and "expressed his solidarity in sharing their suffering, as well as his own pain and shame in especially in the case of injury caused them by clergy or church workers," the Vatican said in a statement.

"Those who have survived abuse have become true heralds of mercy,” Francis himself later told the bishops. For their suffering, he added, "we owe each of them."

Lupe Cantu, of McAllen Valley, Texas, hangs rosary
Lupe Cantu, of McAllen Valley, Texas, hangs rosary beads on a barricade along Benjamin Franklin Parkway as she waits for Mass delivered by Pope Francis in Philadelphia, Sept. 27, 2015.


He also pledged the church's "careful oversight to ensure that youth are protected and that all … will be held accountable."

According to The Associated Press, the pope is creating a new Vatican tribunal to prosecute bishops who covered up for pedophile priests instead of reporting them to law enforcement.

?Victims rights groups have complained that the Catholic Church and its leaders have done too little to address the clergy abuse, which has made headlines in the United States since 2002.

Up to 100,000 U.S. children may have been victimized, Reuters reported, citing a paper by insurance experts that was presented at a Vatican conference in 2012.

Philadelphia, once a bastion of the U.S. Catholic church, especially has been rocked by the clergy sexual abuse scandal, with three grand jury investigations focused on its archdiocese. The last one, in 2011, accused it of leaving more than three dozen priests accused of serious crimes in assignments that might jeopardize others.

Alvaro Bautista, of Camden, N.J., walks with membe
Alvaro Bautista, of Camden, N.J., crosses the Benjamin Franklin Bridge to later hear Pope Francis celebrate Sunday Mass in Philadelphia, Sept. 27, 2015.

Visiting inmates

Late Sunday morning, the pope visited the Curran-Fromhold Correctional Facility. Standing before a throne-like chair that some of the inmates had made by hand from black walnut, Francis – a staunch believer in prison reform and inmates’ capacity for rehabilitation – brought a message of hope to the facility.

"Jesus comes to us so he can restore our dignity as children of God ... to recover our hope, to restore our faith … and to remind us that confinement is not the same as exclusion," the pope said, speaking in Spanish.

Almost 100 men and women inmates, seated in rows of green chairs, appeared to listen intently. Dressed in blue uniforms, some also sported tattoos on their hands, arms and necks.

The pope encouraged them, and "all those who in any way are part of this institution" to "make possible new opportunities, new journeys, new paths."

Some material for this report came from AFP, AP and Reuters.

WATCH: Pope Francis enchants faithful at Festival of Families

WATCH: Pope Francis calls for continued vigilance agianst sex abuse by priests