Cities are places favoured by a source of income. Cities are places that must rely on written records. It is through writing that they will tally their goods, put down the laws that will govern the community and establish title to property. Cities are places that are intimately engaged with their countryside, that have a territory that feeds them and which they protect and provide services for. Cities are places distinguished by some kind of monumental definition, that is, where the fabric is more than a blanket of residences.
Cities are places of buildings and people.
Kostoff's definition is interesting, and one which most people would probably be comfortable with. If we can agree that there is much about our cities that is worthy of conserving, and that it is important to think in terms of their character, it becomes particularly relevant because it effectively demonstrates that conservation is not just about physical form, but must include many other considerations.