The separation between Nature and urban environment is a matter of facts in contemporary cities. Nature and animals do not benefit of any privileged conditions in urban contexts as human predominance is exaggerated. The aim of our project is to give a new meaning to the water infrastructure of the Navigli system and to exploit their flowing within the city to bring back Nature in the city. Along the canals, one or multiple boundaries will be elevated to create a fertile environment for animals and vegetal species where they can reproduce, live and proliferate. The boundary, permeable for animals, yet inaccessible for humans, is made of sticks arranged to support bamboo modules to host the nest of multiple animal species. The project is modified by and adapts to the context, rising and lowering according to the height of the surrounding environments.