BIG cities pack a punch equal to some national economies. Tokyo and New York, for example, have a GDP roughly equal to that of Canada. These cities will continue to hold the top spots in 2020, according to PricewaterhouseCoopers, a consultancy. Paris's high position is more of a mystery, however, given the poor performance of the French economy in recent years. Although the top 15 is dominated now by the developed world, by 2020 more emerging-market cities, such as São Paulo, will feature.

AFP