The project for a Cité de l'Eau is at the heart of the rehabilitation of two 19th-century industrial buildings, along the A86 next to the Seine. The SIAPP, whose activity is water treatment, includes offices, laboratories, training rooms and archives. The project is both simple and rational, showcasing an oblong volume that groups together all the departments. Stretched out the length of the 19th-century building, the translucid block leaves an important area free for possible cultural events.