The notion of landscape reflects two inseparable realities. Landscape is a "sight" that may be considered both an objective and material reality, as well as a subjective perception. There is no landscape without someone to observe it: in order to exists, a landscape must be seen and contemplated. This essay on Charleoi's slag heaps questions the status of a landscape in a urban context and highlights diverse definitions attributable to a landscape scupted by slag heaps - the last vestige of Charleroi industrial period - and its evolutions in time. Yet, implies the existance of a space on which our eye and conscience act, this space has its own existence, if not an identity, depending on the representation, that people have on it. Lastly, this essay also proposes a viable landscape study, placing slag heaps in a future dynamic based on ecology and also on the equilibrium of the space where they are developing, whether enviornmental or human.