Dr John Rich & John Rich 
City in Late Antiquity [PDF ebook] 

The city was the nexus of the Roman Empire in its early centuries. The City in Late Antiquity charts the change undergone by cities as the Empire was weakened by the third-century crisis, and later disintegrated under external pressures. The old picture of the classical city as everywhere in decline by the fourth century is shown to be far too simple, and John Rich seeks to explain why urban life disappeared in some regions, while elsewhere cities survived through to the Middle Ages and beyond.