Arnsberg, town, west central Germany, in North Rhine-Westphalia (Nordrhein-Westfalen), located on a tributary of the upper Ruhr River, in the wooded uplands of the Sauerland. It is a popular resort for the great Ruhr industrial area to the west and a regional transportation and manufacturing center. Founded in the 11th century, Arnsberg retains many old streets and medieval buildings. Population (1997) 78,330.
