This thesis seeks to answer the question of the meaning of the destruction of the urban environment in the 1992-95 Bosnian war. The inquiry begins with the destruction of the Old Bridge in Mostar, Bosnia-Herzegovina. This event constitutes an exemplary instance of the destruction of urban environments. The destruction of the Old Bridge is not, however, an isolated event: urban destruction was widespread during the Bosnian war. It is argued that a clue to the meaning of this destruction lies in the fact that it is shared spaces that are destroyed. The `logics' of urban destruction are then considered. Such destruction cannot be properly Accounted for by either the traditional notion of military necessity or the regimes established to protect cultural heritage. Rather, it is argued that the destruction of urban environment comprises `urbicide'. Urbicide is defined as the destruction of that which characterises the urban: heterogeneityI.t is argued that destroying buildings represents the destruction of the conditions of possibility of heterogeneity. The thesis then addresses the relation between shared spatiality and heterogeneity. Drawing on Heidegger's account of Being-in-the-world, it is argued that existence is both spatial and shared. The fundamental sharing of existential spatiality constitutes existence as a heterogeneous Being-with-others. The Heideggerian notion of Mitsein (Being-with) is proposed as an initial account of the nature of this heterogeneity. This account of Mitsein is developed through a consideration of the work of Jean-Luc Nancy. In particular the implication of Being in community is noted. An account is given of the politics of Being-with at stake in urbicide. In conclusion it is argued that urbicide comprises an ethno-nationalist attempt to cover over the Heterogeneous nature of existence. The proper starting point for a response to ethno-nationalist violence must be a recognition of the heterogeneity and community at stake in urbicide.