Stagg field, at the university of chicago, is where radioactivity was discovered. the first nuclear pile was built. nuclear fission was discovered. nuclear fusion was discovered

Stagg Field, at the University of Chicago, is where the first nuclear pile (the Chicago Pile-1) was built.

Explanation:

The Chicago Pile-1 was an American nuclear reactor research reactor at the University of Chicago. On December 2, 1942, the scientists created the first controlled chain reaction using the reactor.

Chicago Pile-1 was part of the Manhattan Project, the American attempts to build an atomic bomb, during World War II. It was located in a former squash court under Stagg Field's western stands. Stagg Field had been the home arena for the university's American football team and was located relatively centrally in Chicago. The project was led by Italian nuclear physicist Enrico Fermi, who had dropped out of the United States when he received the Nobel Prize in physics in 1938.