The "Tribute in Light" is a visual memorial to those who were lost on Sept. 11, 2001, and is turned on for every anniversary. The lights go on at sunset on Sept. 11 and go off at dawn on Sept. 12.
The beams, coming from 88 searchlights south of the World Trade Center site, were first put in place six months after the attack and are now a yearly tradition.
At full power, the lights can be seen for many miles, depending on the weather.
The Tribute in Light ended at daybreak Thursday.