This thesis offers a detailed examination of the ideas of the city and of citizenship in the writings of Plato, Aristotle, Cicero and Augustine in their historical contexts. Aristotle is considered as a critic of Plato and Augustine of Cicero, with Cicero considered as poised between Plato and the Stoic legacy. The aim of this examination is to test certain still dominant assumptions about ancient citizenship, defined as active participation in government. These assumptions are that ancient citizenship was primarily political, secular, adult and male; that it is best articulated by Aristotle; that it is compromised by Rome in practice and by Cicero in theory and finally abandoned by Augustine through a Christian denigration of the importance of political life in time. Cicero and Augustine are rather thought to inaugurate an alternative modern idea of citizenship as the non-participatory receiving of rights and protection from the sovereign state. I conclude instead that ancient citizenship was primarily by birth, was first to do with religious rather than political participation and included women and children. Aristotle’s purely political picture of civic origins and of citizenship is therefore misleading. Moreover, Aristotle’s views on citizenship turn out to be contradictory and incoherent, just because he has lost the primary religious referent. Individual virtue oriented ultimately towards the eternal therefore comes into conflict with collective justice. By contrast, Plato’s theory of metaphysical participation is exactly suited to conceiving political participation and retaining a continuum of citizenship across the human ages and classes. Cicero is caught between this Platonic vision and a Stoic, proto-liberal one, and the same goes for Rome itself. Its aspects of empire and monarchy can be seen as according with Platonic mixed constitution and universalising ambition. Augustine, by virtue of his Christian outlook, perfects a Platonic version of Rome, just as his Trinitarian grounding of participation, including political participation, perfects the Platonic metaphysics of the super-forms of the One, the Dyad and their interaction.