Originally published in 1913 and initially delivered as lectures in the University of London, this book provides a survey of the Roman Empire as a 'vast federation of commonwealths', rather than large provinces divided by language or nationality. Reid reasserts the importance of municipalities as institutions that were fundamental to the structure of the entire imperial government, and examines how the municipal organizational scheme was deployed in various territories of the Empire over time. The evidence for the impact of this system is drawn from archaeological, artistic, and historical sources. Wide-ranging in its scope, this book will be of value to anyone with an interest in the practical management of the Roman Empire.