By Jean-Louis de la Vaissiere and Jennie Matthew
Pope Francis has spent an emotionally-charged day in New York from morning prayers at the 9/11 Memorial to a drive past adoring masses thronging Central Park.
Leading a gathering of 700 at the site of ground zero, the Pope paid tribute to the nearly 3000 victims and those who were first in line responding to the September 11 attacks.
The head of the world's 1.2 billion Catholics led a multi-faith prayer for world peace and a sombre moment of silence bringing together Hindu, Buddhist, Sikh, Greek Orthodox, Muslim and Jewish leaders.
"In this place of pain and remembrance, I am full of hope," the 78-year-old Argentine said.
"I hope our presence here sends a powerful sign of our wish to share and reaffirm the wish to be forces of reconciliation, forces of peace, of justice."
After an impassioned early morning speech at the United Nations, and the grave solemnity of ground zero, Pope Francis was welcomed in song and laughter on a warmly emotional visit to a Catholic school in New York's East Harlem neighbourhood Friday afternoon.
From Harlem, Francis set off in direction of Central Park, already teeming with tens of thousands of people hoping to catch a glimpse of him on his way to evening mass in Madison Square Garden.
Earlier in the day, the Pope went to the UN General Assembly to offer his vision of a better world.
In a wide-ranging speech, Francis touched on an array of hot-button topics, including the persecution of Christians, the Iran nuclear deal, drug trafficking - "silently killing millions" - and the rights of girls to an education.
The first Latin American pope - who has seen his own country suffer economic crises - called on the UN Security Council and financial lenders to "limit every kind of abuse and usury".
He also gave his latest passionate plea to protect the environment, as he voiced confidence that a looming UN summit on climate change would reach effective agreement in Paris.
The Pope offered a strong endorsement of Iran's agreement with the United States and five other world powers to limit its nuclear program, a day after he spoke to the US Congress, where many lawmakers vehemently oppose the deal.
Francis reserved some of his strongest words for drug trafficking, a scourge in Latin America in particular.
"Drug trafficking is by its very nature accompanied by trafficking in persons, money laundering, the arms trade, child exploitation and other forms of corruption," he said.