Because of its strategic position, Luxembourg was, from the 16th century until 1867, when its walls were dismantled, one of Europe's greatest fortified sites. It was repeatedly reinforced as it passed from one great European power to another: the Holy Roman Emperors, the House of Burgundy, the Habsburgs, the French and Spanish kings, and finally the Prussians. Until their partial demolition, the fortifications were a fine example of military architecture spanning several centuries.
The City of Luxembourg is located at the crossing point of two major Roman roads. In 963 Sigefroid, a count from the Moselle valley, built a castle on the Rocher du Bock, which he obtained by means of an exchange with the Abbey of St Maxirnin of Trier. His servants and soldiers settled around the castle and the modern town sprang from the market-place of this settlement, the Vieux Marche. Settlers were recorded as early as 926 in the Alzette valley, near the castle, and their houses formed the nuclei of the later lower towns of Grund and Pfaffenthal.
The town had grown to such an extent that a second defensive waU was built aronnd the end of the 12th century, but this, too, was superseded in the 15th century when a third line of defences was built, enclosing the lower town of Grund as well.
By the 16th century, Luxembourg with its fortifications had become a strategic and military prize. The House of Burgundy, the Habsburgs, the French and Spanish kings, or the Holy Roman Emperors - all wanted Luxembourg. It was this reason that the city remained within the confines of its fortifications until 1867. Life there was harsh and the inhabitants resented having soldiers billeted upon them.
Throughout this period the defences of Luxembourg were continually extended and improved, making it into a fortress that earned the title of the "Gibraltar of the North". This was a dubious distinction, since it brought the city into most of Europe's wars from the 16th to the 18th centuries. Four main stages can be identified:
1. 17th century (especially 1671-84): enlargement of the defences by the Spanish, who built several new redoubts (Peter, Marie, Berlaimont), and construction of the first barracks inside the city.
2. 1684-97: large-scale rebuilding of the fortifications under the direction of Vauban following the successful siege of 1684 by the French. Pfaffenthal was included within the defences and large barracks were built on the Rham and Saint-Esprit plateaux. The Saint-Esprit monastery was transferred to Pfaffenthal.
3. 18th century: continued development of the fortress by the Austrians (from 1715). The engineer de Beam% prepared an ambitious plan designed to make Luxembourg a key element in the defence of the Austrian Netherlands. This work, which lasted over forty years, involved the construction of new forts around the city (eg those of Thtigen and Olisy) and systems of casematesli nked by underground tunnels.
4. 19th century: the Grand Duchy of Luxembourg joined the German Confederation after the Congress of Vienna and the federal fortress of Luxembourg was garrisoned by the Prussian Army from 1815 to 1867. The Prussians carried out major renovation work from 1826 onwards (eg at Fort Thtingen, where the surviving remains, known as Les Trois Glands, date from this period) and also added new elements, such as Fort Wedell, built to protect the railway station, which was built at around this time.
With the signature of the Treaty of London in 1867 the European powers confirmed the perpetual neutrality of the Grand Duchy and, in consequence, the evacuation of the fortress within three months and the demolition of the fortifications. This brought to an end a long evolution over nine centuries and turned a grim fortress of some 180 ha into an open city. Dismantlement of more than 24 km of underground defences and some 40,000 m2 of casemates, batteries, barracks, and the like lasted sixteen years and cost over 1.5 million gold francs. Some elements survive, such as twelve of the 28 gates and a number of redoubts and forts.