Hanford's B Reactor is a unique artifact of the beginning of the nuclear age. It is not only a well-preserved example of the first generation of nuclear reactors, it is actually the first production-scale nuclear reactor every made. Completed in 1944, it produced plutonium for the world's first atomic bomb, the Trinity test on July 16, 1945, and for the bomb that destroyed Nagasaki on August 9, 1945. The reactor's place in U.S. history is indisputable, as is its key role in world history. In short, when humanity first learned how to tap the energy of the atomic nucleus -- a milestone in human evolution -- it was first put to use at B Reactor. And that first step still stands as a solitary structure in the desert of southeastern Washington state.