The motivation for this thesis emerged from my growing questions on the architecture practice. My interest for the collectives and its respective dissemination in the past years were the starting point for this study. Through a long and tortuous way, the research has grown into a complex project. The project touches upon topics of social democracy, political issues, economics, spatial planning and governance. The city of São Paulo is socially and urbanely unbalanced. Three factors contributed to the unbalance: The fast disorderly growth of the city, the impacts of a complex governance structure for city development, and the planning tradition that still presents difficulty in implementing the proposed guidelines. All these elements are related to the theories exhaustively researched; the spatial justice, the right to city, open source architecture and the new economical devices have formed the foundation for my spatial design in a contested area of downtown São Paulo. Therefore, this thesis presents itself as an experimental process to include participation in urban development. The specific area of Largo do Arouche in downtown São Paulo was chosen as the test site in order to achieve more tangible results within participation and the issue of implementation. The design choices were based on the Municipal Master Plan and on the input of theoreticians and practitioners I gathered through the research. The visions presented as final design react to the municipal plan showing the possible short-term changes in the local scale. Finally, the main idea of my project is to create an open space for citizens to interact and intervene in order to co-create and to transform their own space of conviviality. This will encourage coexistence and the establishment of new bonds within the community. The proposed interventions are intended to make the space more democratic, inclusive and civic.