Brussels, officially the Brussels Region or Brussels-Capital Region, is the de facto capital city of the European Union (EU) and the largest urban area in Belgium. It comprises 19 municipalities, including the City of Brussels proper, which is the constitutional capital of Belgium, the seat of the French Community of Belgium and of the Flemish Community. Brussels has grown from a 10th-century fortress town founded by a descendant of Charlemagne into a metropolis of more than one million inhabitants.