The Tribute in Light is a visual memorial to those who died on September 11, 2001, and is turned on for every anniversary.
The lights go on at sunset on September 11 and go off at dawn on September 12.
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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.
Check out pictures of the tribute through the years.
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Each year, New York City and millions around the country commemorate 9/11 with mournful ceremonies, volunteering, appeals to "never forget," and drawing attention to the terror attacks' continued toll on first responders.
Relatives of the victims descend on ground zero in Lower Manhattan, and the events of that terrible day and the weeks, months and years that followed are never forgotten, nor are the memories of those killed by terrorists in hijacked planes.
Additionally, we remember all those who have died from 9/11-related illnesses from their heroic work at ground zero and those who suffer today.
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September 11 still shapes American policy, politics and everyday experiences in places from airports to office buildings, even if it's less of a constant presence in the public consciousness after 20 years.
The 9/11 commemorations are by now familiar rituals, but each year at ground zero, victims' relatives infuse the ceremony with personal messages of remembrance, inspiration and concern.
CLICK HERE for more Eyewitness News reflections, photos and stories marking the anniversary of 9/11
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