"A three-year review into the future of air travel around London is due to finish with the recommendation that a new runway be built at one of two existing airports. But while the capital gingerly edges towards airport expansion, other parts of the world are witnessing a massive airport building boom."
. It cites a very lengthy list, but some of them are:
Home to major stock exchanges and indexes
Influential in international political affairs
Home to world-renowned cultural institutions
Service a major media hub
Large mass transit networks
Home to a large international airport
Having a prominent skyline