Keywords: Roman Italy; Urban Systems; Rank-Size Analysis.
Based on archaeological data, this paper argues that at the start of the imperial period Roman North Italy had at most four cities which exceeded Pompeii in terms of physical size. Rank-size analysis shows that in this period the urban system of Roman North Italy also had a far less hierarchical appearance than the urban system of the same region at the start of the seventeenth century. The urban system of Roman Italy as a whole was dominated by the primate city of Rome, but if Rome is eliminated from the picture, the rank-size distribution for peninsular Italy also looks decidedly non-hierarchical. The most likely explanation is that, with the obvious exception of Rome, which was sustained by the resources of a vast empire, Roman Italy had a "modular" urban system which offered limited scope for the accumulation of resources in unusually large cities.