France, officially the French Republic, is a country primarily located in Western Europe. Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the North Atlantic in North America, the French West Indies, and many islands in Oceania and the Indian Ocean. Metropolitan France shares borders with Belgium and Luxembourg to the north; Germany to the northeast; Switzerland to the east; Italy and Monaco to the southeast; Andorra and Spain to the south; and a maritime border with the United Kingdom to the northwest. Its metropolitan area extends from the Rhine to the Atlantic Ocean and from the Mediterranean Sea to the English Channel and the North Sea. Its 18 integral regions—five of which are overseas—span a combined area of 632,702 km2 (244,288 sq mi), with a total population estimated at 69.1 million in 2026. Its capital, largest city and main cultural and economic centre is Paris. Metropolitan France was settled during the Iron Age by Celtic tribes known as Gauls before Rome annexed the area in 51 BC, leading to a distinct Gallo-Roman culture. In the Early Middle Ages, the Franks formed the kingdom of Francia, which became the heartland of the Carolingian Empire. The Treaty of Verdun of 843 partitioned the empire, with West Francia evolving into the Kingdom of France. In the High Middle Ages, France was a powerful but decentralised feudal kingdom, but from the mid-14th to the mid-15th centuries, France was plunged into a dynastic conflict with England known as the Hundred Years' War.