France, officially the French Republic is a sovereign state comprising territory in western Europe and several overseas regions and territories. The European part of France, called Metropolitan France, extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean. France spans 643,801 square kilometres (248,573 sq mi) and has a total population of 66.6 million. It is a unitary semi-presidential republic with the capital in Paris, the country's largest city and main cultural and commercial centre. The Constitution of France establishes the state as secular and democratic, with its sovereignty derived from the people.