Poelzig's single best-known building is the enormous and legendary I.G. Farben Building, completed in 1931 as the administration building for IG Farben in Frankfurt am Main, now known as the Poelzig Building at Goethe University. In March 1945 the building was occupied by American Allied forces underEisenhower, became his headquarters, and remained in American hands until 1995. Some of his designs that were never built included one for the Palace of the Soviets and one for the League of Nations headquarters at Geneva.