Enrico Fermi, an Italian theoretical and experimental physicist, is best known for his work and development of Chicago Pile-1, the world’s first nuclear reactor to achieve a stable, self-sustaining nuclear chain reaction.
Chicago Pile-1 was constructed beneath a rackets court at the University of Chicago as part of the wider Manhattan Project and consisted of a large pile of uranium and graphite blocks assembled in a flattened ellipsoid shape. The reactor went critical on 2 December 1942 at 3:25 PM, with lead scientist Enrico Fermi confirming that the reactor was achieving a self-sustained chain reaction. It remained operational for 28 minutes, producing 0.5 watts of energy (enough to power a small lightbulb), before being shut down. Following Pile-1’s success, it was deconstructed and moved to Red Gate Woods - the future site of the Argonne National Laboratory.