Metropolization is not a new phenomenon: metropolises have been around for centuries. The prime and permanent function of a metropolis is the coordination of economic activities at a world scale. This function has been applied to different activities in history, depending on technological conditions and economic organization, and consequently it generated different forms of metropolises. The resulting continuities and discontinuities in the metropolises' evolution can be understood in terms of agglomeration economies. In the pre-industrial period, the trading metropolis coordinates long range trade. The industrial revolutions generate new needs for coordination of production and give rise to the manufacturing metropolis. Finally, the information revolution and the emergence of the post-industrial economy create the global metropolis.
