Urban Aggregation outlines an alternative approach toward the development of public land in Cape Town. Recognizing the current sale of public land for private development and the subsequent privatisation of the city thereof as problematic, the dissertation puts forward a new approach, arguing for an expanded role of the architect in city-making processes. Together with the resistance of the privatisation of the city, Urban Aggregation seeks to uncover an architecture which can incorporate many agencies into the process of development, and allow an open-ended outcome (architecture) to emerge, which undermines the deterministic spatial product usually resulting from current modes of private development. Taking lessons from the theory of the Commons, new ways of thinking about the city are uncovered, which shifts the imperative of housing development from Modernist consumption towards a Constructionist view of housing as a social and collective process, attempting to balance the obvious need for private development within the city with a sense of public accountability to which this type of development should be held. This dissertation thus takes on an expanded role of architecture and the architect. Recognizing the critical need for architects to partake in the design of processes of development, this dissertation embraces the architect as the designer of systems of Aggregation, instead of the designer of specifics.