France, officially the French Republic, is a country whose territory consists of metropolitan France in western Europe, as well as several overseas regions and territories. 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 span a combined area of 643,801 square kilometres which, as of October 2017, has a population of 67.15 million people. France is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban centres include Marseille, Lyon, Lille, Nice, Toulouse and Bordeaux.
During the Iron Age, what is now metropolitan France was inhabited by the Gauls, a Celtic people. Rome annexed the area in 51 BC, and held the region until 486, when the Germanic Franks conquered the region and formed the Kingdom of France. France emerged as a major European power in the Late Middle Ages following its victory in the Hundred Years' War.