#UChicago scientists working to achieve the first nuclear chain reaction often held top-secret discussions inside Eckhart Hall. Outside on the Quad, the “Council Tree” became a popular spot to take a rare but welcome break. “We needed an opportunity for informal talk,” said project scientist Herbert Anderson in August 1976. “Sitting under this tree gave us that chance.” The tree has since been lost to Dutch elm disease, but otherwise the site appears as it did in 1942. #Nuclear75