Paris is today one of the world's leading business and cultural centres, and its influences in politics, education, entertainment, media, fashion, science, and the arts all contribute to its status as one of the world's major global cities. In 2009 and 2010 Paris was ranked among the three most important and influential cities in the world, among the first three "European cities of the future" – according to research published by the Financial Times and among the top ten most liveable cities in the world according to the British review Monocle.Paris also ranked among the ten greenest European cities in 2010. Paris hosts the headquarters of many international organizations such as UNESCO, the Organisation for Economic Co-operation and Development (OECD), the International Chamber of Commerce (ICC) and the informal Paris Club.
Paris and the Paris Region, with €552.1 billion in 2009, produces more than a quarter of the gross domestic product of France.According to 2008 estimates, the Paris agglomeration is, scantily after London, Europe's second biggest city economy and the sixth largest in the world. The Paris Region hosts 37 of the Fortune Global 500 companies in several business districts, notably La Défense, the largest dedicated business district in Europe.According to the latest survey from Economist Intelligence Unit in 2010, Paris is the world's most expensive city in which to live.With about 42 million tourists per year (28 in city proper of which 17 million are foreign visitors, Paris is the most visited city in the world. The city and its region contain 3,800 historical monuments and four UNESCO World Heritage Sites.