The story started from the invisible river Senne on the urban scale of Brussels, concentrating on the wall which is both spolia on site and the identity of my youth center. The archaeological idea of Spolia keeps me discovering the existing value, then constantly thinking of collecting, composing and re-using. Once existing fragments collide with new ones, the process of bricolage comes up. The wall on site is the ghost of Senne that could be seen as spolia on immaterial, but now it became the backdrop of people’s lives in the neighborhood, where the youths there are facing issues such as stigmatization. The strategy of the urban proposal and architectural part is to use the wall as a frame to turn the situation from segregation and at the meanwhile to break youths’ mental wall. The old wall owns the collective memory, speaks for space. That’s why the walls teach.