After World War II, the rapid growth of nuclear physics and chemistry meant that research needed more and more powerful accelerators, which required large areas. The University of Paris, the École Normale Supérieure and the Collège de France looked for space in the south of Paris near Orsay. Later some of the teaching activity of the Faculty of Sciences in Paris was transferred to Orsay in 1956 at the request of Irène Joliot-Curie and Frédéric Joliot-Curie.