Library, concert, and reading room—the Hans-Sachs-Haus has been a multifunctional building from the beginning, dedicated to cultural events. The industrial town of Gelsenkirchen, up-and-coming in the 1920s, wanted to present itself as a modern city. After the war, large parts of the exceptional heritage of brick expressionism had been destroyed or damaged. In recent years, gmp Architekten have built a new building into an old façade, as a successful example of building within existing structures. In this volume, the responsible architects present their approach and show the particularities of this task by means of plans and images. The architecture journalist Dirk Meyhöfer illuminates the significance of this building in a detailed essay, as well as the conversion in the context of the historical development of the Ruhr area.