EUPEN (Fr. Néau), a town of Germany, in the Prussian Rhine province, in a beautiful valley at the confluence of the Helle and Vesdre, 9 m. S. of Aix-la-Chapelle by rail. Pop. (1905) 14,297. It is a flourishing commercial place, and besides cloth and buckskin mills it has net and glove manufactories, soapworks, dyeworks, tanneries and breweries, and also carries on a considerable trade in cattle and dairy produce. It has a Protestant and four Roman Catholic churches, a Franciscan monastery, a progymnasium, an orphanage, a hospital, and a chamber of commerce. As part of the duchy of Limburg, Eupen was under the government of Austria until the peace of Lunéville in 1801, when it passed to France. In 1814 it came into the possession of Prussia.