It is a commonplace to describe twentieth-century Modernist architecture as utopian, but doing so arguably has less to do with putative social agendas than with explaining the failure of such work to deliver on extravagant promises. By interrogating utopian declarations for twentieth-century architecture and visionary urban representations, the aim of this article is to sharpen the loose pairing of Modernist architecture and Utopia. Consideration is also given to how undue emphasis on representation supports post-rationalisations of failure as the inevitable teleology of Utopia, which serves only to empty architecture of its ethical function. To conclude, some preliminary thoughts on the prospects of a more convincingly utopian modern architecture are advanced.