Monday marks the 16th anniversary of the terrorist attacks that happened in New York City, Washington D.C. and Pennsylvania on Sept. 11, 2001. That day 2,977 people were killed as terrorists hijacked commercial airplanes and flew them into the World Trade Center, the Pentagon, and a field in Pennsylvania. The National September 11 Memorial & Museum in New York City will hold a memorial ceremony Monday morning celebrating the lives of those lost on that day, and the lives lost in the bombing of the Twin Towers on Feb. 23, 1993.

The ceremony will begin at 8:46 a.m. EST and will be streamed live on the museum's website here. The museum itself will be closed to the general public on Monday, but open to family members of the victims.

On Monday night, the “Tribute in Light” commemorative public art installation will take place across the New York City night sky. The tribute shoots two beams of light into the sky to represent the Twin Towers, destroyed in the attack. The display can be seen from a 60-mile radius around lower Manhattan, according to the Museums website.

The Memorial Plaza around the museum and former site of the World Trade Center will be open from 3 p.m. to midnight.

On Sept. 11, 2001, four planes ultimately crashed in the U.S. after being hijacked in a coordinated terrorist attack.

The first plane hit the north tower of the World Trade Center at 8:46 a.m. killing the crew, passenger and hijackers instantaneously. At 9:03 a.m. a plane crashed into the second tower of the World Trade Center. At 9:37 a.m. that day, a plane crashed into the Pentagon. The hijackers, passengers and crew were killed along with 125 military and civilian personnel that work at the Pentagon. A plane flying over Shanksville, Penn., crashed into a field at 10:03 a.m. after several passengers and the pilots stormed the cockpit in an attempt the win control of the plane from the hijackers.