Red Gate Woods

Red Gate Woods is a forest preserve section within the Palos Forest Preserve, a division of the Forest Preserve District of Cook County, Illinois. It is located near where the Cal-Sag Channel meets the Chicago Sanitary and Ship Canal. In the woods is the original site of Argonne National Laboratory and the Site A/Plot M Disposal Site, which contains the buried remains of Chicago Pile-1, the world's first artificial nuclear reactor.

This section of the forest preserves, then code named "Argonne" was leased by county commissioners to the Manhattan Project in the 1940s and 1950s. After its initial tests, the reactor at Stagg Field at the University of Chicago was removed and reassembled at the Metallurgical Laboratory site in these woods.

Source: Wikipedia