LOWER MANHATTAN, N.Y. (PIX11) — The Tribute in Light has become an iconic part of the 9/11 remembrance.

PIX11 got a behind-the-scenes look at how it all comes together. Organizers completed a test run ahead of the 21st anniversary this weekend.

The light installation is assembled on the roof of the Battery Parking Garage, just south of the 9/11 Memorial. One by one, the switches are flipped manually to illuminate the night sky, honoring every life lost on Sept. 11, 2001, and those who have died since due to related illnesses.

Alice Greenwald is president and CEO of the 9/11 Memorial and Museum, which presents the Tribute in Light. 

“It is about memory and the loss of the buildings and the souls of the people going up to the heavens,” said Greenwald.

Wednesday evening, PIX11 News got a first peek at the light installation that has become part of the events marking the somber commemoration of 9/11 each and every year. The production team put on the finishing touches, and the rehearsal went off without a hitch. The team says to pull it off, it uses the amount of power equivalent to an entire New York City apartment building.

“One of the biggest things we have to overcome here is bringing all the power up to the building, which takes about two days of bringing cables that we bring to the roof,” said Scott Campbell of Michael Ahearn Production Services.

The twin beams reach four miles into the sky –  and are made up of 88, 7-thousand watt xenon lightbulbs positioned into two 48 ft. squares, the beams representing the shape and orientation of the original Twin Towers.

“We designed a custom installation and mounting enclosure that relies on the threads of a screw to tilt the light from side by side,” said Michael Hemmenway, with lighting designer Fisher Marantz Stone.

For the second year in a row, organizers have partnered with other buildings throughout the city that will also light their facades and rooftops in sky blue to create an extension of the tribute in light. They’ll illuminate the city, echoing the enduring spirit of New Yorkers and echoing the mantra Never Forget. 

“That gave this city a sense of hope, a sense of something that would be transcendent out of this terrible moment,” said Greenwald.

The Tribute in Light will be presented from dusk to dawn on the night of September 11th. It can be viewed from a 60-mile radius around Lower Manhattan.