EmmaontheLoose in the capital of Argentina. With a city this big, there is only one way to get around. Vespa. Greater metropolitan Buenos Aires has an estimated population of 9,677,000, making it the sixth largest in the world and the third largest in the Western Hemisphere. Approximately 13 million live in the Province of Buenos Aires, which is roughly equal to that of Chile, but in an area about the size of Italy. Many thanks to the Buenos Aires Vespa Club.