New York's annual Tribute in Light illuminated the sky on Tuesday night, sending beams high into the air to commemorate the 18th anniversary of the 9/11 terror attack. /VCG Photo

The commemorative public art was assembled on the roof of a garage building south of the 9/11 Memorial, and the twin beams echoed the shape of the twin towers of New York's then landmark World Trade Center. /VCG Photo

On September 11, 2001, members of terror group al-Qaida hijacked two airplanes, crashing them into the twin towers and killing nearly 3,000 people. /VCG Photo

To honor those killed in the attack, the art installation was presented six months after 9/11 and has become an annual memorial event. /VCG Photo