Luxembourg or Luxemburg, city (1991 pop. 75,377), capital of the Grand Duchy of Luxembourg, S Luxembourg, at the confluence of the Alzette and Pétrusse rivers. It is a commercial, banking, industrial, administrative, and cultural center as well as a rail junction. First established by the Romans on a defensive site inside the rivers' meanders, it was known by the Saxons as Lucilinburhuc [little fortress]. Luxembourg developed around a 10th-century castle that was one of Europe's strongest fortresses until the garrison was dismantled according to the terms of the Treaty of London (1867).
The original nucleus of the city, in the upper town, consists of numerous medieval houses and churches, the most notable of which are the Grand Ducal Palace and the Cathedral of Notre Dame (both 16th cent.). Newer features such as the city hall and the Chamber of Deputies, as well the National Museum of Art and History and the city history museum, are also located there. The modern upper town to the west is a busy commercial center bordered by a complex of parks that replaced the old fortifications. On the Kirchberg Plateau to the northwest are Radio-Television-Luxembourg, the Grand Duchess Joséphine-Charlotte Concert Hall, the Grand Duke Jean Museum of Modern Art, and several institutions of the European Union, including the European Court of Justice, the European Investment Bank, and the Secretariat of the European Parliament. The lower town, in the winding valley bottoms, is mostly industrial. The entrenched meanders of the rivers are crossed by spectacular bridges, including the Adolphus Bridge and the Bridge of Europe. The city is the seat of a university (founded 1958).