This paper relates a comparative approach to the urbanisation processes of the valleys in Brussels and Montreal by the students of the atelier d’urbanisme opérationnel from the graduate master program in urbanism and spatial planning at UCLouvain (Belgium). During the atelier students have been working on a historical and prospective reading of the industrial valleys within the Brussels and Montreal metropolitan areas, subject in both cases to a strong real estate pressure. The purpose of the atelier was to investigate on the urbanisation processes with a special focus on mixed uses produced inside the valley by the proximity of residential and industrial spaces. The comparison between the images of the students’ projects, historical images and images of ongoing development projects have been envisioned for the subsequent research as a tool to understand how the student’s projects addressed the local and historical contexts. The work aims to contribute to the ongoing planning debate in Brussels, searching for the potentials of building resilience as well as maintaining productive activities inside the valley.