Saint-Denis, city (1990 pop. 122,875), capital of the French overseas department of Réunion. It is a port on the Indian Ocean at the mouth of the St.-Denis River and exports sugar and rum. St.-Denis is Réunion's largest city and its administrative, communications, and economic center. Industry is related to food processing for local consumption. Arabs play a leading role in the city's commerce. The Institute for Legal, Economic, and Political Studies (1950) is there. St.-Denis was founded in the late 17th cent. as a French way station to Asia.