The administration of cities within the provinces was seen to by local political authorities.
The Romans attempted to use the Greek concept of the city-state whenever possible, but in conquests without a structure already in place they would establish an organization on a pre-existing tribal basis. The local nobility or wealthy aristocrats would be enrolled in this city government functioning much like the Republican Roman Senate.
They would see to regular daily administration, maintaining order and collecting taxes.
Later in the Empire, Imperial Procurators were appointed to various major cities to oversee financial matters, especially concerning the collection of taxes.
They could either work for the provincial governor or report directly to the Emperor.
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After the systematic organization of the administration in the 2nd century, the title of procurator was reserved for functionaries of the equestrian class.