Sweeping through the landmarks of America's biggest city, Pope Francis on Friday offered comfort to 9/11 victims' families at ground zero, warnings to world leaders at the United Nations and encouragement to schoolchildren in Harlem as he mixed the high and low ministry so characteristic of his papacy.

In the early evening, he led a jubilant parade through Central Park past a crowd of about 80,000 and celebrated Mass at Madison Square Garden, usually the site of basketball games and rock concerts but this time the scene of a solemn service celebrating New York in all its diversity.

"Living in a big city is not always easy," Francis told 18,000 people at the Garden, easily one of the most respectful crowds the arena has ever seen. "Yet big cities are a reminder of the hidden riches present in our world in the diversity of its cultures, traditions and historical experiences."

Francis' itinerary for his only full day in New York was packed with contrasts befitting a head of state dubbed the "slum pope" for his devotion to the poor. He moved from the corridors of power to the grit of the projects with lush Central Park in between.

He drew huge, adoring crowds while also managing to connect one-on-one with countless New Yorkers, despite extraordinarily tight security that closed off many streets and kept most spectators behind police barricades.

"As he passed by, you felt a cool, refreshing peace, as if he were spreading a huge blanket of peace through the crowd," Ruth Smart of Brooklyn said of the procession in Central Park. "Even though the crowd exploded in a roar, it was pure joy."

On Saturday morning, he flies to Philadelphia for a big Vatican-sponsored rally for Catholic families. As many as 1 million people are expected for the closing Mass on Sunday, the last day of Francis' six-day, three-city visit to the U.S., the first of his life.

As Friday's Mass came to a close with a sustained and thunderous roar of applause, the toll of the long day seemed evident as an exhausted Francis walked with assistance down the stairs of the altar. The Vatican spokesman said Francis, who suffers from sciatica and a bad knee, is feeling the effects of missed physiotherapy appointments while he's been on the road but still has energy for the final two days of the trip. (Associated Press)