On July 16, 1945, the world’s first nuclear bomb was detonated at the Trinity Site in the New Mexico desert, near Alamogordo. Code-named “The Gadget,” this top-secret test was part of the Manhattan Project, the U.S. effort to develop atomic weapons during World War II. The explosion produced a yield of about 20 kilotons of TNT, creating a blinding flash visible for miles and a mushroom cloud over 40,000 feet high. The test demonstrated the unprecedented destructive power of nuclear energy and ma