In Zürich the Sihl is an elusive urban site and a functioning back to the city proper. Although considered a backside, it is counter-intuitively partly a front setting that is equal representative as the Limmat. This project emphasises the backside nature of the Sihl by allowing new rules and systems to create a new urban figure. No longer just a linear river but a comb-like figure is creating a new collective structure and questions the conventions of architecture’s role in urban planning.