ABSTRACT
The physical fabric of cities, once established, changes only slowly. But the nature of the economic and social activity undertaken within that fabric may be transformed rapidly-within decades rather than over decades. And in any case the overall balance of that activity may shift as the physical fabric is extended, pushed ahead as the population and the income of each city increases. These changes will reflect a redefinition of the role played by each city within the wider national society and within the international economy.
