Special Agent David Beach of the Secret Service, which was in charge of protecting the pope, said the high level of security was "one of those necessary evils" in staging a large event.

"We're responsible for the pope's safety but also the safety of all those attendees," he said. "I think we were successful in that mission."

Others disagreed with the tactics to accomplish that.

Austen Ivereigh, author of a definitive papal biography, who covers Pope Francis for news organizations like the BBC, said security in Philadelphia was wildly over the top, beyond the strict measures imposed when three million people saw the pope in Rio de Janeiro in 2013.

"If that was excessive," Ivereigh said, "this was pathological."

Hundreds of thousands of people, many from across the country and around the world, came to see the pope here on Saturday and, especially, at an outdoor Mass in front of the Art Museum on Sunday.

But untold numbers became trapped in massive backups at the Secret Service checkpoints that offered the only access to the Benjamin Franklin Parkway. Some people spent five hours in line, missing the Mass.

"It was just too strict. Every person had to be checked so thoroughly, the whole thing just collapsed," said Jack Valero, a coordinator with Catholic Voices, who was in Philadelphia to advise the World Meeting of Families.

Philadelphia Archbishop Charles J. Chaput said the church had little input on security measures, adding that "if we had it our way, we would have probably had it much simpler."

Chaput said he was hesitant to criticize the officials responsible for the security of the pope and people who came to see him.

"If they weren't kept safe, all blame would go there," he said.

When the pope visited Cuba on his way to the United States, security was not nearly as dramatic, he noted. But that country had not endured the 9/11 attacks or the Boston Marathon bombing, which "have made us very, very sensitive to the possibility of terrorism," Chaput said.

Mayor Nutter said the Secret Service moved people through checkpoints as quickly as it could.

"It's not like they were trying to delay folks," he said.

Several people who spent Sunday stuck in lines said they were nonetheless happy to be near the pope, to share fellowship with fellow Catholics, and to have participated in the World Meeting of Families. Still, they struggled to understand how a year of planning could result in a huge, dissuasive iron ring in Center City.

People who made it as far as the checkpoints found themselves forced to surrender the wooden sticks of small papal flags, hard-plastic water bottles, and apples and other round fruits that were considered possible projectiles.

The Rev. Thomas Wray, who led a 30-person delegation from the Archdiocese of Cincinnati, said he was shocked by "Berlin Wall-like, irrational Secret Service 'checkpoints.' "

"They knowingly blocked access to a First Amendment-protected religious exercise of free speech," Wray said. "That just isn't American."

Wray reached the Parkway through a clergy-access entrance. But only two people in his group got through security screening to the Parkway.

"It really did feel Orwellian," said Wray, director of religious education at the Cincinnati Archdiocese. "It felt provocative. There was a swagger to the feds, 'This is our town, this is our event.' "

Secret Service spokesman Robert Hoback said the agency had warned that waiting times could be two to three hours, which was the average time Sunday.

Antoinette Malone, 68, of South Philadelphia, said she spent five hours in line trying to reach the checkpoint on 20th Street.

Beside her was a group of young people who had driven from Wisconsin, seminarians from Connecticut, a woman with four young children, and a woman in a wheelchair.

During the long wait, she said, no official approached the crowd to explain the delay, estimate the wait time, or say if they might still get inside. She had advanced to within a few yards of the checkpoint when she realized the Mass was over.

"The crowd was smaller than estimated, so how could something like this happen?" she asked. "Why weren't there more stations and people to man them?"

Malone, a parish member at Epiphany of Our Lord and a lifelong resident of Philadelphia, was proud to see the city host Pope Francis, to step out on a world stage.

But "if we want to continue as a first-class city, and we want more events to come, they should find out why this happened and take steps to improve it," she said. "It felt like we were forgotten."

Cinelli, the retired teacher, said he and his wife were staying near St. Charles Borromeo Seminary after traveling here to see the pope.

On Saturday they were on City Avenue, waiting for the pope to pass as he was driven to Center City. Around them were nuns and other faithful, along with a contingent of state and local police and National Guard soldiers.

When Francis appeared, a nun ran toward his car and "was intercepted," Cinelli said. "She wasn't brought to the ground, but she was definitely restrained by one of the soldiers."

That evening he and his wife went to the Parkway to watch the papal parade. The crowd was huge, people packed shoulder to shoulder. One line of people, saying security officials told them to exit toward the Art Museum, tried to move through an impassable crowd.

That led to arguments, challenges to fight, and one frustrated young woman screaming profane threats.

The next day, Cinelli said, he went to St. Joseph's University, hoping to see the pope when his car passed on the way to Mass. A National Guardsman shouted at him not to cross the street - he had not intended to - but also not to stay where he was, and not to go back in the direction from which he came.

"National Guardsmen started coming into the crowd," Cinelli said. "That presence got really heightened. . . . It was clear that National Guardsmen were not just protecting things, but they were ready to jump at the slightest."