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). The city of Paris, within its administrative limits (the 20 arrondissements) largely unchanged since 1860, has an estimated population of 2,211,297 (January 2008), but the Paris metropolitan area has a population of 12,089,098 (January 2008), and is one of the most populated metropolitan areas in Europe. Paris was the largest city in the Western world for about 1,000 years, prior to the 19th century, and the largest in the entire world between the 16th and 19th centuries.
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 or the informal Paris Club. Paris is considered one of the greenest and most liveable cities in Europe. It is also one of the most expensive.
Paris and the Paris Region, with €552.1 billion (US$768.9 billion) in 2009, produce more than a quarter of the gross domestic product of France. According to 2008 estimates, the Paris agglomeration is Europe's biggest or second biggest city economy and the sixth largest in the world. The Paris Region hosts the headquarters of 33 of the Fortune Global 500 companies, the highest such concentration in Europe, hosted in several business districts, notably La Défense, the largest dedicated business district in Europe. The Paris region has the highest concentration of higher education students in the European Union, is the first in Europe in terms of research and development capability and expenditure and is considered one of the best cities in the world for innovation. 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.