The Pope prayed at the World Trade Center memorial and met with survivors and the families of 9/11 victims during his tour of New York City on Friday.
It was a somber note in what has been a rapturous visit to New York. Pope Francis led an interfaith service late on Friday morning.
He also visited the United Nations, where he was driven through the corridors in an electric vehicle. He addressed the General Assembly and called for world leaders to help the poor and combat climate change.
"The ecological crisis, and the large-scale destruction of biodiversity, can threaten the very existence of the human species," he said.
His Holiness addressed the Assembly in both Spanish and English.
He told the world leaders: "You worry about the future of the planet, and what kind of a world we will leave for future generations. But today, and every day, I would ask each of you, whatever your capacity, to care for one another. Be close to one another. Respect one another."
Last night, Pope Francis drove triumphantly along Fifth Avenue, which was lined with thousands of spectators as the rarely-heard bells of St. Patrick's Cathedral pealed across Manhattan.
As he entered the Cathedral, the Pope spotted 17-year-old Stephanie Gabaud from White Plains, New York, who is confined to a wheelchair. He took time to hug her, talk with her and bless her.
He led an evening prayer service and laughed when he was told by Cardinal Dolan: “Once you entered those famous doors, you became an official New Yorker.”
John Boehner, a devout Catholic described the Pope's visit as "thrilling" and "emotionally overwhelming."
Boehner made a surprising announcement on Friday, just one day after he welcomed the Pope to Capitol Hill he's resigning.
The House Speaker is calling it quits after 25 years in Congress and in typical Boehner fashion, he could not stop crying.
Boehner made headlines on Thursday when the Pope spoke in Congress; he was shedding tears from the moment the Pontiff began to speak
Watch Below: Meet the Nuns Who Are Making Communion Wafers for Pope Francis' Visit