During Morgenstern's visit to Princeton University, Adolf Hitler took over Vienna through the Anschluss Österreichs and Morgenstern decided to remain in the United States. He became a member of the faculty at Princeton but gravitated toward the Institute for Advanced Study. There, he met von Neumann and they collaborated to write "Theory of Games and Economic Behavior", published in 1944, which is recognized as the first book on game theory. Game theory is a mathematical framework for the study of strategic structures which govern rational decision-making in certain economic, political and military situations. In 2013, the University of Vienna relocated the Faculty of Business, Economics and Statistics and named the square Oskar-Morgenstern-Platz in his honor.