The cities of the Roman Empire were, on the whole, plural societies, which had in them significant sub-groups, ethnic, religious, or, indeed, both together — for the two categories were still only sometimes distinguishable. Such an environment carries many resonances for us and it is surprising to realize its neglect as a subject for study. The classical Greek polis had been a theoretically homogeneous institution of look-alike citizens, with outsiders excluded or enslaved. The notional Roman approach was, in the early days, to deal with outsiders by assimilating them. When we look at the cities of the Hellenistic kingdoms, we observe that they often did consist of several racial elements, though how these were accommodated has been for some time an issue for debate, and this remains an open question. But beyond that, our concern seems to stop.