The era of independent cities arose around 10,000 BC. Conditions in these early cities were very unsanitary due to the accumulation of trash. Cities rose 2 feet every 25 years from dirt and trash. 
The cities always reserved certain lands for public pasturage and for use in case of siege; these “commons” represent the survival of the earlier form of collective ownership.  Primitive men feared someone's home after death which delayed its destruction and delayed the establishment of permanent cities.  Cities devoted to manufacture, and trade arose ca. 8000 B.C.  The Dravidians were among the earliest peoples to build cities and to engage in an extensive export and import business, both by land and sea. 
When men met unarmed on the sacred market place these market squares became the first places of sanctuary and later known as “cities of refuge.” Any fugitive was safe there.  The purpose of an ancient city wall was to protect against ferocious beasts as well as to prevent surprise attacks by hostile humans. 
In a real commonwealth the business of governing cities and provinces is conducted by experts and is managed just as are all other forms of economic and commercial associations of people.  In a continental nation of a neighbor planet cities have no taxing power, neither can they go in debt.