The city, for reasons of its location and natural geography, has through history been a place of strategic military significance. The city developed around a 10th century castle on the Bock. The city was further fortified in the 14th century. These fortifications remained until the citadel was dismantled in 1867, when the Duchy of Luxembourg attained independence and asserted neutrality. This neutrality was disregarded by Germany on the occasions of both World War I and World War II when Luxembourg was invaded.
Places of interest include the Cathedral of Notre Dame and the city hall. The city is the seat of a university, Radio Luxembourg, and several institutions of the European Union, including the European Court of Justice and the European Investment Bank, the preponderance of which are located in the area of the city known as Kirchberg.