The city of New York has a special way of remembering the horrible terrorist attack on September 11th, 2001. Two light beams formed by 88 searchlights shine up to the sky near the former site of the Twin Towers. Originally designed by Ezra Orion in 1997 as an art installation on top of the Twin Towers for the 4th of July celebration, the idea was dismissed as too expensive. However, after the attacks the installation came to life with a very different and strong meaning. The "Towers of Light" can be seen beaming for 97 km up the sky on clear nights and serve as a strong message of commemoration. The city overlooks this public art installation with a caution to environmental issues. In collaboration with American non-profit environmental organization New York City Audubon, they have worked out the problems caused by the lights to migrating birds and also managed to collect used cooking oil from local restaurants to produce biodiesel, fueling of the Lights.