It is difficult to define in a word or through one writer what modernism is. But it is absurd to exclude James Joyce in discussing modernism, because his work occupies a remarkable position in the topography of modernism. It would be more deductive to understand what modernism is through Joyce. Modernism is usually defined as being based on the modern life in a cosmopolitan city. The shift of weight from the country life to the urban one is not simply the change of places, but rather the displacement of aesthetic focus. Joyce`s lifelong concern is only about Dublin, even when Joyce lived in European cities, exiled from the Irish capital. His remark on the restoration of Dublin from his own work reveals how deep compassion Joyce must have had for the city. Dublin was the second largest city in the British empire, but rather a city under colonial surveillance and control. Joyce`s Ulysses, based on the colonial Dublin, inevitably complicates the topography of modernism in that Joyce is the proto-writer of modernism. The urban space is the locus of new literary movements at the turn of the century. Many writers and artists gathered to form different artistic movements and ideologies. Michel Foucault`s definition of a history of spaces as the history of powers from the great strategies of geo-politics to the little tactics of the habitat is relevant in discussing Joyce`s Ulysses. Joyce`s Dublin reveals "the great strategies of geo-politics," e.g. Ireland under the British imperial domination, and "the little tactics of the habitat," that is, the modern life of Dubliners. Joyce`s picture of Dublin in Ulysses encapsulates the paradoxical significance of urban aesthetics in that a city life cannot be understood as a whole totality, because too many people live independently of one another. In this respect, Joyce`s urban aesthetics is based on nomadic life, not on residentiary one.