Iserlohn is a city in the Märkischer Kreis district, in North Rhine-Westphalia, Germany. It is the largest city by population and area within the district and the Sauerland region.

The Märkischer Kreis is a district (Kreis) in central North Rhine-Westphalia, Germany. Neighbouring districts are Unna, Soest, Hochsauerland, Olpe, Oberbergischer Kreis, Ennepe-Ruhr, and the city of Hagen.