During the ceremony, six moments of silence were held, marking when each of the World Trade Center towers was struck and fell. It also marked the times corresponding to the attack on the Pentagon and the crash of Flight 93.
New York City Mayor Michael Bloomberg, Speaker of the House Nancy Pelosi and Senate Majority Leader Charles Schumer were also in attendance.
This year marks the 20th anniversary of the 9/11 terrorist attacks, which killed nearly 3,000 people and altered the state of our world forever.
"We never forget. We never forget the children who have grown up without parents. Parents who have suffered without children. Husbands and wives who had to find a way forward without their partners. Brothers, sisters, loved ones," President Biden wrote on Instagram. "Jill and I hold you close in our hearts."