“City of a Thousand Fires” was once Gelsenkirchen’s nickname, a reference to the dense concentration of blast furnaces at the height of its coal and steel production. Tangible remnants of that era are the workers’ housing developments, which continue to shape the Ruhr region today.1 Their building typologies can be broadly divided into three phases. Beginning around 1850, the “D-Zug” developments were built: simple one- to one-and-a-half-story row houses stretching up to 200 meters, with separate entrances leading to small independent units. Beginning in the 1870s, there were semi-detached houses for two families, followed by four-family houses in cross-shaped layouts, and around 1900 garden colonies emerged.