During his remarks, Philadelphia Fire Commissioner Adam Thiel said it's critical that we remember how we felt and what we saw.
"I think it is that spirit of taking care of each other that we must continue to learn from today," said Thiel. "Because if ever there was a time that we all need to take care of each other, this is that time."
The ceremony included a bell ringing that honored the 343 New York City firefighters and paramedics, 60 New York City police and port authority officers and all of the 2,977 victims who died in the World Trade Center, the Pentagon and the hijacked planes.
RELATED: 9/11 Timeline: How the September 11 attacks unfolded
"It almost becomes more real every year living and working in Center City, those images resonate more than they did when I was a kid living in rural Wisconsin," said attendee Josh Simpson of Old City.
Mayor Jim Kenney said we'll never forget how our country changed in an instant but should feel inspired that to this day, even in the middle of a pandemic, strangers are still helping strangers.
"I've also been thinking about how our country came together to rebuild we did not let fear take over our lives," said Kenney. "I'm sure we can all agree that this year has tasked us once again to come together as a country as we face difficult and very uncertain times."
This annual ceremony was hosted by The Philadelphia Flag Day Association and the Philadelphia Fire Department.