Until the end of the 19th century, the Flon River flowed through the city of Lausanne in the open air to feed sawmills and mills. Around 1830, the upper middle class of Lausanne used to take the Promenade des Eaux, from the Place du Nord to the Place du Vallon, to go to the baths. Halfway along the route, the Pavillon des Eaux housed a staircase leading to a source of ferruginous water with medicinal properties. The promenade, not maintained, fell into ruin, and the pavilion was destroyed. When the river was filled in in 1890, the promenade and its name were erased from the map. No trace of the water remains today. The project proposes to reconnect the two squares, and to improve the contact with the buildings bordering them. This new river serves as an axis whose fulcrum anchors on the North Square and reconnects to the downtown area. The upstream catchment basin receives water from the tunnel and from the hills, and the canal is a system that prevents flooding of the lower part of the city, which happens more and more frequently due to global warming.