Pope kicks off a jam-packed day in NYC

Pope Francis will deliver his first address before the United Nations, where a record number of world leaders are expected to convene. The Vatican flag was raised at the U.N. to welcome the pontiff.

The pontiff will also be visiting the 9/11 Memorial and Museum, and Central Park, in the second leg of his three-city visit to the United States.

No one knows exactly what the pope will say to the General Assembly, but if his speeches so far are any indication, he will not shy away from controversial topics including abortion, climate change and the refugee crisis.

On Thursday, Francis urged Congress to reject what he called a "mindset of hostility" toward refugees and undocumented immigrants.

"We must not be taken aback by their numbers, but rather view them as persons, seeing their faces and listening to their stories, trying to respond as best we can to their situation," the pope said.

The U.N. calls the flood of refugees from the Middle East now spreading into Europe the greatest humanitarian crisis of the century. The pope sees himself as a diplomat of sorts, and during Francis' General Assembly address, he is expected to touch on that crisis once again.

Throughout his first trip to America, the Argentinian-born pope has urged everyone, from his flock to politicians, to love one another, and has been "spreading the news" from the moment he arrived.

Shortly after his jet, dubbed "Shepherd One," landed at John F. Kennedy International Airport Thursday, Francis was serenaded by Frank Sinatra's iconic "New York, New York" tune amid cheers.

Minutes later, the pontiff was whisked to Manhattan by helicopter, where he took his trusty papal Fiat to his popemobile -- the open-air Jeep -- which put him in full-view of thousands who longed for a glimpse of the Holy Father.

As Pope Francis took a drive down Fifth Avenue, many raised their smartphones, trying to capture the moment he looked their way.

"A breath of fresh air, a terrific leader and we need that here in our country," one person said.

"He treats everyone equally because all of us are the same," another said.

St. Patrick's Cathedral played host to 2,500 faithful.

"Papa Francesco, welcome to St. Patrick's Cathedral," New York's Cardinal Timothy Dolan said, blessing his divine company.

After addressing the General Assembly, the pontiff will head to the 9/11 Memorial and Museum to visit the reflecting pools and participate in a wreath-laying ceremony, reports CBS News correspondent Chip Reid. He will also meet with relatives of those lost in the 9/11 attacks, then lead an interfaith prayer service inside the museum.

Security will be tight, but that's to be expected. The NYPD will have more than 6,000 officers assigned to keeping the pontiff safe during his New York stay.

Francis will be the second pope to visit ground zero. Pope Benedict visited in 2008, and prayed in the very spot where the Twin Towers once stood.

In the afternoon, Francis will ride in his popemobile through Central Park in front of 80,000 people. The pope will enter on west 72nd Street, then travel down the west side of the park.

As CBSN's Elaine Quijano reports, there are multiple layers of security in place at the park.

Almost the entire bottom half of the park is closed, and a mile-long fence has been built to help secure the parade route.

Ninety-three thousand people entered a lottery to get tickets for Friday's event - 80,000 of them were made available. There are reports that church officials were upset after learning that some people were trying to scalp their free tickets on Craigslist.

The popemobile Francis will use is the same Jeep Wrangler he used in New York Thursday night and in Washington earlier this week. In August, four popemobiles were flown in and dropped off in D.C., Philadelphia and New York - including one extra.

Quijano spoke to some people who told her they aren't Catholic but want to be at the parade because they like Francis's message of tolerance and unity.

Following his trek through the park, Francis will make his way down to Madison Square Garden, where he will celebrate Mass for an estimated 20,000 people.