Drones have been used to recreate the Twin Towers in the New York City skyline ahead of the 25th anniversary of 9/11. The public art installation, called '2,977 Lights Over New York Harbor' was created with help from victims’ families, survivors and emergency responders. A total of 2,977 drones were deployed, representing each person killed in the 2001 attacks. The drones spiralled into a helix before forming the outline and original dimensions of the Twin Towers above the city. #September11 #TwinTowers #NewYork #America #C4News