Paris is the capital and largest city of France. It is situated on the river Seine, in northern France, at the heart of the Île-de- France region (or Paris Region, French: Région parisienne). As of January 2009 the city of Paris, within its administrative limits (the 20 arrondissements) largely unchanged since 1860, has an estimated population of 2,234,105 and a metropolitan population of 12,161,542, and is one of the most populated metropolitan areas in Europe.
An important settlement for more than two millennia, Paris had become, by the 12th century, one of Europe's foremost centres of learning and the arts and the largest city in the Western world until the 18th century. 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. It hosts the headquarters of many international organizations such as UNESCO, the OECD, the International Chamber of Commerce and the European Space Agency. Paris is considered one of the greenest and most liveable cities in Europe. It is also one of the most expensive cities.
Paris and the Paris Region, with €572.4 billion (US$759.9 billion) in 2010, produce more than a quarter of the gross domestic product of France and is, along with London, Europe's biggest city economy and one of the largest in the world. The Paris region is the first in Europe in terms of research and development capability and expenditure and through its 17 universities and 55 grandes écoles has the highest concentration of higher education students in the European Union. With about 42 million tourists annually in the city and its suburbs, 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