Luxembourg officially the Grand Duchy of Luxembourg, is a small landlocked country in western Europe, bordered by Belgium, France, and Germany. Luxembourg has a population of under half a million people in an area of approximately 2,586 square kilometres (999 sq mi). Luxembourg is a parliamentary representative democracy with a constitutional monarch, ruled by a Grand Duke. It is the world’s only remaining sovereign Grand Duchy. The country has a highly developed economy, with the second highest Gross Domestic Product per capita in the world (U.S. Central Intelligence Agency 2007 est.). Its historic and strategic importance dates back to its founding as a Roman era fortress site and Frankish count's castle site in the Early Middle Ages. It was an important bastion along the Spanish road when Spain was the principal European power influencing the whole western hemisphere and beyond in the 16th - 17th centuries. Luxembourg is a founding member of the European Union, NATO, the United Nations, Benelux, and the Western European Union, reflecting the political consensus in favour of economic, political, and military integration. The city of Luxembourg, the capital and largest city, is the seat of several institutions and agencies of the European Union. Luxembourg lies on the cultural divide between Romance Europe and Germanic Europe, borrowing customs from each of the distinct traditions. Luxembourg is a trilingual country; German, French and Luxembourgish are official languages. Although a secular state, Luxembourg is predominantly Roman Catholic.