Starting from a port, Marseille was born as the result of improvisation and spontaneous architectures rather than urban planning. Same things happened in the architecture scale. architects are not the only doers of architecture. Long after the building has been made the non-architects continuously do architecture. When non-architects occupy space, they start to ‘do-it-themselves’. In most cases, they do this in an already occupied territory, where the activity of doing architecture has been classified and claimed by architects - the rules have already been established. But there are also some space occupations that are out of the rules, such as squatting, vendors, graffiti, protest. They, like “pet architecture”, do not necessarily create appealing spaces, and some are even illegal, but they can highlight people’s demands and show people’s bottom-up determination to shape the city. When people do the practice, they mainly based on their own current needs and what material they have instead of considering the building or city as a whole. These practices are spontaneous, unplanned makeshift and ad hoc. They can be seen as improvisational practice. Seen architecture as paintings, in these cases, their improvisational activities are more like a collage rather than fully considered composition. But as Jencks explains, it involves using an available system in a new way to solve a problem quickly and efficiently. By doing so, it offers a way for everyone to shape and discuss the city they live in. And for the public, there should be nothing preventing them, in an agonistic and participatory manner, from devising and debating forms of their shelter and space for daily life. The improvisational practice has itself taken inspiration: Another world is possible.