“Sky Ladder,” a pyrotechnic artwork by Cai Guoqiang, a Chinese contemporary artist currently living and working in New York City. Cai is best known for using gunpowder in his spectacular works. Sky Ladder, released at Huiyu Island Harbour, Quanzhou, Fujian, June 15, 2015 at 4:49 am, approximately 2 minutes and 30 seconds.