Since 2000, declarations issued in rapid succession by the international community have aimed at setting goals to drastically improve the living conditions of slum dwellers while, in the same time, the slums dwellers increased by 4,5% per year in Africa. Simultaneously, we have witnessed changes in the manner in which city residents perceive space: in today's city, the relationship between places and flows constitutes the new living space and sense of belonging (Castells, 1996). With the changes in the information society, space of flows are transformed into power flows, concentrated in space of flows which dominates more and more space of places, peripheriques areas where flows takes place everyday. Using this theory as grid, it is to re-examine the evolution of urbanization in African cities and their shantytowns. Indeed, this process of domination of the space of flows has implications for the planning approaches and uses of space of place in slums. This dual vision, putting power to the flows of space valued by the elites'cities of the living spaces of places experienced by people, is used to observe, name and understand the past and the future of cities. These elements have resulted in the formulation of a number of questions that have served as guidelines for this research. This research first targets the development of the urbanization process and the role of precarious neighborhoods: what measures are now being implemented by the authorities to reconcile the need to improve the competitiveness of African cities (advocated by donors) with the expectations of people in poor neighborhoods? In a second phase, the role of these neighborhoods' community areas is evaluated: are they a media to be valued and included in the projects to restructure the neighborhoods? Two assumptions have emerged from said questions. The first concerns the process of urbanization in African cities. This involves an analysis of the balance of power between the application of modernizing planning practices and the use of space by the residents of the neighborhoods. The second questions the role of community spaces as efficient public areas within the framework of projects to upgrade the neighborhood. The expected results of this thesis aim i) to understand the evolution of these precarious areas in the building of African cities, ii) to learn about the place and the role of community spaces and to learn from neighborhood upgrading projects. For this study, two cities were chosen: Douala (Cameroon's economic capital) and Kigali (Rwanda's political capital). For each, two methodological perspectives were adopted: the first is a comprehensive study of the entire city, based on plans, planning documents, interviews with local officials, archive documents; and the second is as a local study carried out in a market area of the city, based on observations, interviews, a questionnaire developed from a representative sample of traders, and a social and spatial analysis of the neighborhood. This approach is therefore comparative (two cities and two districts), multi-scale (two scales of analysis), historical (identifying cultural, social and political customs) and interdisciplinary (even holistic to a certain extent, taking into account different disciplines such as law, economics and urban sociology). Ultimately, this study reveals both the local specificities and differences of each city. These dissimilarities were largely developed in the presentation of these territories. They are indeed important, especially for the city of Kigali, which is undergoing a process of post-genocidal reconstruction. However, it also appears that each city's path contains a significant number of common characteristics, mainly linked to the responses they provide to urban problems: globalization today tends to standardize practices. The first element common to both areas is urban duality. This process occurs first in an urban form. The African city today remains a binary geographical entity: the city that separated the indigenous people from the settlers was succeeded by a post-colonial city marking the separation between the inherited formal city and the informal city in creation. This urban confrontation can be seen as a form of inertia, defined as a rectilinear uniform advance, suitable for the fabric of the city. The analysis of the evolution of city planning shows that projects have failed to break this logic. The delay accumulated in this field since the 80s had the effect of amplifying the phenomenon. Furthermore, this duality is reflected in the urban power struggle between the authorities and the inhabitants. On the one hand, the authorities seem determined to reproduce and keep constant both tension with and distance to the population, seeking to maintain their social control over the population. On the other hand, residents of poor neighborhoods regularly claim a "right to the city". This inertia does not mean a lack of change. This manifests itself through urban crises which temporarily break the balance. A new order is then implemented, replicating the urbanization process that prevailed in the old order. In a second phase, this research highlights the struggle for territory which emerges in these African cities. Indeed, in the midst of the general trend of inertia and reproduction, a few evolutions are worth mentioning. There is first of all a real spatial and social fragmentation of urban areas. This process occurs both in the slums and the formal rich neighborhoods mushrooming more and more on the outskirts of the city (near the urban ring roads serving these new places in which to live). To this diversification of territorial situations can be added an increasing number of slum upgrading projects, the results of which fail to meet the original targets. Moreover, even within neighborhoods, there is a fragmentation of community spaces, such as markets. The latter have undergone an important evolution since the 80s, sometimes leading to conflict between this type of local trade and the business carried out in shopping malls, which is claimed to be modern. The influence of the space of flows and the implementation planning process promote liberal "modern" sector, consisting of subsidiaries of large corporations, supermarket chains to a upper class people, while causing profound changes in space with neighborhood markets. The challenge of planning for the city of tomorrow appears to reduce this duality and to take into account this duality to prevent the development of precarious neighborhoods and urban fragmentation.