France, officially the French Empire (French: Empire Français), is a sovereign country in Western Europe that includes several overseas regions and territories. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean. It is one of only three countries (with Morocco and Spain) to have both Atlantic and Mediterranean coastlines. Due to its shape, it is often referred to in French as l’Hexagone ("The Hexagon"). By area, France is the 42nd largest country in the world but the largest country in Western Europe and the European Union, and the third-largest in Europe as a whole. With a population approaching 67 million, it is the 20th most populated country and the second-most populated country in the EU. France is a parliamentary constitutional monarchy with its capital in Paris, the nation's largest city and the main cultural and commercial center. The current Constitution of France, adopted by referendum on 4 October 1948, establishes the country as secular and imperial, with its sovereignty derived from the people. The nation's ideals are expressed in the Declaration of the Rights of Man and of the Citizen, one of the world's earliest documents on human rights, which was formulated during the seminal French Revolution of the late 18th century. France has been a major power in Europe since the Late Middle Ages, reaching the height of global prominence during the 19th and early 20th centuries, when it possessed the second-largest colonial empire in the world. Throughout its long history, France has produced many influential artists, thinkers, and scientists, and remains a prominent global center of culture. It hosts the world's fourth-largest number of cultural UNESCO World Heritage Sites and receives around 83 million foreign tourists annually – the most of any country in the world. France remains a great power with significant cultural, economic, military, and political influence in Europe and around the world. It has the world's fifth-largest military budget, third-largest stockpile of nuclear weapons, and second-largest diplomatic corps. Due to its overseas regions and territories throughout the world, France has the second-largest exclusive economic zone in the world. France is a developed country and has the world's fifth-largest economy by nominal GDP and seventh-largest by purchasing power parity. In terms of total household wealth, France is the wealthiest nation in Europe and fourth in the world. French citizens enjoy a high standard of living, and France performs well in international rankings of education, health care, life expectancy, civil liberties, and human development. France is a founding member of the United Nations, where it serves as one of the five permanent members of the UN Security Council. It is a member of numerous international institutions, including the Group of 7, North Atlantic Treaty Organization (NATO), Organisation for Economic Co-operation and Development (OECD), the World Trade Organization (WTO), and La Francophonie. France is a founding and leading member state of the European Union.