[en] From its inauguration in 1960 to its registration by the UNESCO in the World Heritage List in 1987, Brasilia has been the universal materialization of the project of the modern city: avant-garde and ideal. Nowadays it has become an urban concentration of 3 million inhabitants, vast and fragmented. It surprises by its sprawl, its widespread and repetitive spatial patterns, its urban networks relying mostly on automobile, its residential enclosure and the huge gap between the social classes – the poorest bearing the burden of an unequal access to centrality and development. Yet, at its foundation it was meant as a true public locus of urban encounter, on its building site as well as its workers' settlements. Nowadays where and how do the populations of Brasilia develop an integrated society? How could a project of an integrated city, delimited, with its own boundaries, conceived as the melting pot, turn into such a fragmented society, with a widening gap between the social classes, a widespread urbanisation and an environment far too open to individual housing initiatives? Could this urban and social shift of Brasilia, from a closed city, product of a totally utopian ideal of social integration, to an open and segregated city, be interpreted as an exemplary testimony of the primacy of economic dynamics over urban designs? From an urban environmental perspective, crossing Brazilian and French urban geographies, the authors address the crucial question of the conservation of Human Heritage represented by Brasilia's inner city and the multiple risks the agglomeration has to deal with nowadays. They explore the current knowledge on the short history of this specific urban structure and finally show how the original unsustainable urban utopia leads to a declining quality of life and a decaying urban environment for all the categories of the society. They question not only the meaning of local development but also the 21st century urban dilemma between unequal liberalism and balanced social policies. Do we have to accept as inevitable urban forms without any social ties, segregated cities against their social nature, when they are hard to sustain?

[fr] Brasilía a incarné la ville moderne avant-gardiste et idéale des années 1950. Ce projet utopique, confié à un urbaniste, Lucio Costa, et un architecte, Oscar Niemeyer, résiste au temps car, près d'un demi-siècle après sa fondation, la ville jouit toujours d'une aura puissante. L'Unesco a classé le site patrimoine mondial de l'humanité en 1987 mais Brasilía est aujourd'hui au cœur d'une agglomération de trois millions d'habitants d'une incroyable vitalité. Elle surprend par sa composition spatiale distendue, dispersée et répétitive, sa communication urbaine essentiellement automobile et une apparente et inquiétante anomie sociale. Mais où donc et sous quelle forme les populations de Brasilía font-elles aujourd'hui société ? Comment d'un projet de ville délimitée et finie a-t-on pu aboutir à une telle urbanisation diffuse et ségréguée de l'environnement régional ? Les auteurs de cet ouvrage proposent une analyse de cette expérience urbanistique et sociale unique, et s'interrogent sur le sens du développement local et le dilemme urbain du XXIe siècle entre libéralisme inégalitaire et projet social régulateur.