In 1945, the first atomic bomb arrived partly assembled at its test site in the New Mexico desert, on this Friday the 13th. By Sunday, it was completed and set at the top of a tower waiting for the first atomic bomb test the next day. On Monday 16 Jul 1945, it was successfully exploded and the nuclear era began. A mere 21 more days later, the world’s first deployed atomic bomb was dropped on Hiroshima, Japan.«