18. Paris, France
The City of Paris is but the core of a built-up area that extends well beyond its administrative limits. Commonly referred to as the agglomération Parisienne, and statistically as a unité urbaine (a measure of urban area), the agglomeration has a 2013 population of 10,601,122, which makes it the largest in the European Union. City-influenced commuter activity reaches well beyond even this in a statistical aire urbaine de Paris (a measure of metropolitan area), that had a 2013 population of 12,405,426, a number one-fifth the population of France, and one that makes it, after London, the second largest metropolitan area in the European Union. Although joined in a single urban tissue, Paris’ lack of administrative and economic cohesion with its suburbs has been a longstanding problem, but a 2016 ‘Metropole of Grand Paris’ economic and environmental initiative covering an 814 square kilometres (314 square miles) area and a population of 7 million, exists since 2016.