The city is a wonderfully complex entity; it can be defined as either a physical space of architecture, or as a people living in a single place, or as both of these. Within these definitions a myriad other elements emerge that make the city a very slippery object of analysis. This is as true of the multiple entities categorised as ‘the Roman city’ as it is of any other urban form. Indeed, the idea that there was a single category, ‘the Roman city’, in the western half of the Mediterranean basin throughout the period of almost half a millennium that is the subject of this book, does not stand up to more than a few seconds’ scrutiny. Indeed, one of the central tenets of this book is that what we see across this huge area and long time-scale is the working out by numerous local communities of their relationship to Rome as expressed through the almost infinite variations on common themes of urban form and urban structures which were first generated in Italy and then adopted and adapted in the provinces. Moreover, analysis of the Roman city has been shaped by a series of explicit and often implicit theoretical positions rather than by any single agreed narrative or type of explanation. Some of these positions have been articulated with reference to social theory, although much that is written on the Roman city has relied on empiricism and reference to an undefined ‘common sense’. The Roman city has also featured in debates among scholars of the Roman Empire over Romanisation (and resistance), imperialism, the economy, cultural identity, discrepant experience, and phenomenology, to name but a few. We do not intend to rehearse these general debates here, nor to summarise the views of other authors (references are provided and these can be read at first hand). Instead we wish here to explain our view of the Roman city in the light of these discussions in order to articulate the conceptual and theoretical positions which underpin the chapters that follow.