France, officially the French Republic, is a sovereign state whose territory consists of metropolitan France in Western Europe, as well as several overseas regions and territories.[XIII] The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean. The overseas territories include French Guiana in South America and several islands in the Atlantic, Pacific and Indian oceans. The country's 18 integral regions (five of which are situated overseas) span a combined area of 643,801 square kilometres (248,573 sq mi) and a total population of 67.25 million (as of June 2018). France is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. France has long been a global centre of art, science, and philosophy. It hosts Europe's third-largest number of cultural UNESCO World Heritage Sites and leads the world in tourism, receiving around 83 million foreign visitors annually. France is a developed country with the world's seventh-largest economy by nominal GDP, and ninth-largest by purchasing power parity. In terms of aggregate household wealth, it ranks fourth in the world.