City in Hessen, West Germany, 72 km/45 mi NE of Mannheim; population (1988) 592,000. It is a commercial and banking centre, with electrical and machine industries, and an inland port on the river Main. An international book fair is held annually. history Frankfurt was a free imperial city from 1372 to 1806, when it was incorporated into Prussia. It is the birthplace of the poet Goethe. It was the headquarters of the US zone of occupation in World War II and of the Anglo-US zone 1947-49.