Bock

Traces of a Roman watchtower of the 4th century have been found near the Fish Market, where the roads from Reims to Trier and from Metz to Liège once crossed; the Reims–Trier road was ceded by Charles Martel, Duke of the Franks, to the Abbey of St Maximin in Trier in 723. Romans and Franks had probably already lived on the rock, though they left only scant archaeological trace of it.

In 963, Count Siegfried was seeking a defensible centre for scattered holdings at Feulen, Hosingen and Monnerich, and at Sarreburg, Berncastel and Roussy. Having failed to secure a site near the Abbey of Stavelot, he approached the Abbot of St Maximin's for the fortification known as 'the castle which is called Lucilinburhuc', on the cliff above the Alzette, trading it for land he held at Feulen in the Ardennes. With Emperor Otto I's consent obtained, the abbot Viker signed the deed on 7 April 963 — the transaction that gave Luxembourg its foundation.

Under Conrad I the castle became the residence of the Counts of Luxembourg, and in 987 a castle chapel was raised at the nearby Fish Market, on the site later occupied by St Michael's Church. The Bock changed hands repeatedly in the following centuries: the Burgundians damaged, took and rebuilt it in 1473, the Habsburgs in 1477, and the Spaniards in 1555. Under Spanish rule in the 1640s, the Swiss engineer Isaac von Treybach reworked the defences to answer the growing power of artillery, and the rock was strengthened with three fortresses — the Large, Middle and Small Bock — separated by cuts in the stone and joined by bridges; little of Siegfried's medieval castle survived the rebuilding.

In 1684 Vauban took Luxembourg for Louis XIV after a month-long siege that flattened the Bock's fortifications outright. He then undertook major additions to the defences, judging the underground passages and chambers as important as the works above ground: the Large Bock, linked to the old town by the Pont du Château, was enclosed within a wall 12 metres high and became the major component of the new fortress. In 1744, under Austrian rule, General Neipperg enlarged the casemates — begun as the cellars of the medieval castle — into a network whose main passage still runs 110 metres and up to 7 metres wide, branching into 25 cannon emplacements, twelve to the north and thirteen to the south, and able to serve as barracks in the event of war, with water drawn from an internal well 47 metres deep.

During the French Revolutionary Wars, in 1794, the city held out against a French siege for seven months; when the garrison finally surrendered, its walls were still unbreached. The French politician and engineer Lazare Carnot judged the Luxembourg fortress 'the best in the world, apart from Gibraltar' — the remark that gave it its name, the Gibraltar of the North.

The fighting ended only with the Treaty of London of 1867, which required the fortifications to be dismantled; the demolition took sixteen years and cost 1.5 million gold francs. The ruins of the old castle survived the levelling, as did the casemates, which remain a major attraction and have received Emperor Joseph II in 1781, Napoleon Bonaparte in 1804, and Grand Duke Henri and Grand Duchess Maria Teresa in 2000.