The Bock is a promontory in the north-eastern corner of Luxembourg City's old historical district. Offering a natural fortification, its rocky cliffs tower above the River Alzette which surrounds it on three sides. It was here that Count Siegfried built his Castle of Lucilinburhuc in 963, providing a basis for the development of the town which became Luxembourg. However, the Romans and later Franks had probably already inhabited the Bock although there is only scant archeological evidence of their presence. There are however traces of a 4th-century Roman watchtower close to the point in the Fish Market where two major Roman roads used to cross, one from Reims to Trier and the other from Metz to Liège.
Over the centuries, Siegfried's fortified castle on the Bock was considerably enlarged and protected with additional walls and defences. In 987, the castle chapel was built at the nearby Fish Market. Today's St Michael's Church stands on the same site. Under Conrad I, the castle became the residence of the Counts of Luxembourg. It was damaged, destroyed, captured and rebuilt on several occasions as the Burgundians (1473), the Habsburgs (1477), and the Spaniards (1555) attacked and took the fortress.
As time passed, the fortifications needed to be adapted to new methods of war based on increasingly strong firepower. During the 1640s under the Spaniards, the Swiss engineer Isaac von Treybach significantly reworked the defences. The Bock was also strengthened with three forts, the Large Bock, Middle Bock and Small Bock (from west to east), separated from each other by cuts in the rock and linked by bridges. As a result, little remained of the medieval castle.
A little later in 1684, on behalf of Louis XIV, Vauban succeeded in capturing the city of Luxembourg during a month-long siege under which the Bock fortifications were completely flattened. Thereafter Vauban, perhaps the most competent fortification engineer of his day, undertook major additions to the defences, realizing that underground passages and chambers were just as important as the surface installations. The Large Bock, connected to the old town by the Pont du Château, was further reinforced. Enclosed by a wall 12 m high, it was the major component of the new fortress.
In addition to these structures, the Bock also included a system of casemates which originated in the cellars of the medieval castle. In 1744, during the Austrian period, these underground passages were considerably enlarged by General Neipperg. The main passage. which still remains, is 110 m long and up to 7 m wide. Branches leading off on either side were equipped with no less than 25 cannon slots, 12 to the north and 13 to the south, offering considerable firepower. In the event of war, the Bock casemates, covering an area of 1,100 m2, could be used as barracks for several hundred soldiers.
Thanks to its defences, in 1794 during the French Revolutionary Wars, the city held out against the French siege for seven months. When the garrison finally surrendered, the walls were still unbreached. The fortifications were finally demolished under the terms of the Treaty of London in 1867. The demolition took 16 years and cost the enormous sum of 1.5 million gold francs.
In 1933, the Bock casemates were opened to the public. During the Second World War, they were used as a bomb shelter able to accommodate up to 35,000 people. In 1994, the casemates were added to the list of UNESCO's world heritage sites, attracting some 100,000 visitors a year. Renovation work and repairs were undertaken in 2008–2009 including the opening up of the mine galleries which contained explosives able to blow up part of the Bock in case of need.References:
The Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.