The essay conceives the interconnectedness between the physical and political dimensions of the built environment as the ‘worldliness’ of architecture, adverting by the use of this term to a distinction that Hannah Arendt makes between earth and world, the former being the natural conditions on the globe, and the latter referring to the interventions needed to make the globe fit for human habitation. Clearly, architecture can be understood as an instrument used to transform the earth into a world. The first part of the essay thus examines architecture through Arendt’s notion of the world. The ambition of this part is to define the political significance of architecture. This perspective leads on to the second part and the second ambition of this essay: to examine the notion of the world from an architectural point of view. Thinking through the medium of architecture deepens Arendt’s understanding of the reality of the world and its political dimension, while it also formulates an agenda for an architecture of the world – a world that by definition is in-common.