Festschrift with expert contributions from 30 years of renaturation and revitalization of a river landscape. Metamorphosis from an industrial area to a modern metropolitan region. 120 years ago, on December 14, 1899, the Emscher Association was founded. The birth of Germany's first water management association was a forced decision, but one that secured the survival of the region. To address the wastewater issues in the area, the Emscher Association completely rebuilt the Emscher system in the first half of the 20th century. The river, as an open sewage channel confined within a concrete corset, significantly shaped the image of the region in the 20th century and was part of the urban landscape in many places. As part of the structural change, the Emscher was given a new role. The renaturation and revitalization of the river landscape became a symbolic project and went hand in hand with the metamorphosis of the area from an industrial zone to a modern metropolitan region. This book brings together a multitude of expert contributions created over a span of 30 years to commemorate the anniversary. Together, they document the various perspectives on the Emscher transformation and the massive efforts required to redesign a complete water system in the midst of one of Europe's largest urban agglomerations.