ABSTRACT This paper draws on Henri Lefebvre’s conception of abstract space to analyze how socio-territorial relations between a variety of public and private actors shape the transformation of the built environment of the Alpine Rhine Valley in western Austria through urban densification. First, the paper conceptualizes abstract space through the duality of land, which is both traded as a market commodity and regulated by the various layers of the state. Lefebvre’s concept is further refined by making it volumetric, in order to analyze how conceptualizations of urban density are the site of negotiations and trade-offs that irrationalize the rational nature of abstract space. Six socio-territorial relations were identified during typical phases of land acquisition and project development, derived from the empirical material resulting from 20 interviews with key stakeholders. The paper thus demonstrates how socio-territorial relations are essential for the conceptualization of urban densification projects, as well as how volumetric abstract space can contribute to de-naturalizing our understanding of the transformation of the built environment.