FPDCC History: or the history of the oldest and largest forest preserve

In December of 2017, I accepted a job with the  Forest Preserve District of Cook County , the largest and oldest forest preserve in the nation.  One of the first programs I worked on was near Red Gate Woods in the Palos Preserve.  By word of mouth I was told that Red Gate Woods was home to the first nuclear reactor in human history.   Wait, what's that   now ?   A nuclear reactor in the middle of a forest preserve?  And not just any nuclear reactor but the very FIRST nuclear reactor in human history??? Like most American history buffs I was marginally aware of  Albert Einstein's  famous letter to President  Franklin Delano Roosevelt ( dated   from   August 2, 1939) that urged President Roosevelt to begin a nuclear research program.  As the story goes,  after Nazi Germany seized uranium mines in Czechoslovakia, several of  Einstein's colleagues convinced him that the Nazis were working to develop an atomic bomb.  Einstein (who had fled Germany in 1933 when Hitler first came