Soren wrote on Dec 2
nd, 2011 at 11:05pm:
Ancient Rome was more 'diverse' than any city then or since - yet it was robustly Roman and there was no notion of plurality of values. Rome was diverse because it was Rome, not because there were a lot of different nationalities living within it.
Rome accommodated no diversity of law and custom. "When in Rome, do as the Romans." You went to Rome to become a Roman, not to be a Nubian in Rome.
It fell when its Romanness was gone and it became a hotch potch of diversity without a strong centre. Same now. A city of diverse populations can be geat only if it has a centre that holds. Diversity is no substitute for a centre. What we see in most of the great cities you listed is that their very core is under assault, deliberately.
The word ghetto comes from the Italian word borghetto. Even the eternal city had its ghettos and subcultures. In Early Rome, the Etruscans had the best parts of Rome which were largely free from malaria - the Tuscus vicus. In later times, the Jews had their ghetto in what is now known as Trastevere. Then there were the various Roman Mystery cults, including the cult of Bacchus, Mithras and Christianity itself.
It's interesting how Etruscan Haruspices and Augurs played such a leading role in decision making in ancient Rome. The Romans "subcontracted" the Etruscan school of Haruspicy whenever there was an important event.
You might get an illusion of monoculturalism from the historians who were part and parcel of the Roman military machine, such as Julius Caesar and Tacitus.
Some ancient Roman historians were not even Roman. An example is Dionysius of Halicarnasus, who was a leading light in the Greek community in Ancient Rome. The Greeks had a greater status in Rome compared with others (They were not regarded as barbarians) and had considerable influences, particularly in the Hellenistic art and architecture of Ancient Rome.