Recently, the focus of international trade has shifted from a national to a sub-national level, with better availability of finer-grained data and new interdisciplinary research. In particular, the « global city » has become a key topic in international trade due to their superior economic performance. Their superiority can be explained by 1) a well-developed infrastructure attracts many different people and companies to concentrate in a dense area, and 2) the global connectivity of world cities gives access to more opportunities and knowledge outside the metropolitan area. These two factors are very closely linked. World-class companies and talented people in the metro area