Large portions of the film were shot on location in and around Chicago, Illinois, including the University of Chicago, Argonne National Laboratory, the Museum of Science and Industry, the Field Museum of Natural History, Michigan Avenue, and the James R. Thompson Center (Atrium Mall). Additional scenes were shot at Yerkes Observatory in Williams Bay, Wisconsin, on Geneva Lake in southern Wisconsin, interiors of the U.S. Capitol were shot at the Wisconsin State Capitol, in Madison, Wisconsin, at Inland Steel (now known as MITTAL Steel) in East Chicago, Indiana, and at a private residence in Barrington Hills, Illinois. Because of the cold Great Lakes winter and filming taking place during record breaking winter weather, unique challenges were present for the cast and crew.