Constitution of the Roman Republic - Lintott, Andrew (Fellow and Reader in Ancient History, Fellow and Reader in Ancient History, Worcester College, Oxford)

Rome acquired her great empire under republican institutions. These institutions were held to be remarkably stable because they were a mixture of monarchy, oligarchy, and democracy, created by natural evolution not by a lawgiver. The Republic was also a classic example of a largely unwritten constitution, like that of Britain, and so it has bearing on modern political theory.