[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?

[pt] Brasíla encarnou a cidade moderna, avanguardista e ideal dos anos 1950. Este projeto utopico, confiado ao urbanista Lucio Costa e ao arquieto Oscar Niemeyer, resiste ao tempo apos meio-século de sua fundação, pois a cidade continua a possuir una auréola potente, que fascina ou repulsa o visitante. A UNESCO, a classificou Patrimônio da Humanidade em 1987, porém Brasíla é hoje o coração de uma aglomeração urbana de 3 milhões de habitantes que apresenta una incrível vitalidade. Ela surprende por sua composição espacial descontínua, dispersa e repetitiva, por sua comuniçacão urbana essencialmente calcada no automõvel e por una aparente e inquietante anomia social. Mas em que lugar e sobre qual modo as populações de Brasíla forman atualmente una sociedade ? Como um projeto de cidade delimitada e acabada pôde chegar a uma urbanização difusa e segregada do meio-ambiente regional ? Portanto, planos foram elabarados para congregar todos no seio da cidade... um verdadeiro espaço público de encontros urbanos heterogêneos existia no momento mesmo da fundação urbana de Brasíla, nos canteiros de obras, nos acampamentos… Os autores desta obra propõem uma analise desta experiência urbanística e social única e interrogam-se sobre o sentido do desenvolvimento local e do dilema do século XXI, que oscilam entre liberalismo fator de desigualdades e projeto social regulador.