Luxembourg's raison d'être juts dramatically out over the Alzette river valley. This cliff served as the principal approach to the town as far back as Celtic and Roman times, until bridges were constructed. The name comes from the Celtic büück, meaning the promontory supporting a castle. Over its farthest point looms the ruined tower of the castle of Sigefroid himself. He founded the fortress Lucilinburhuc in 963; it was expanded, over the centuries, from this dominant point, and finally razed in 1875.
Vertiginous views from here take in the Plateau du Rham across the way, on the right, and, before it, the massive towers of Duke Wenceslas's fortifications, which in 1390 extended the protected area. The blocklike casernes (barracks) were built in the 17th century by the French and function today as a hospice for the elderly. Below them, at the bottom of the valley, is the 17th-century Neumünster Abbey, which, from 1869 to 1984, served as a
prison, and now houses a cultural and arts center.
Here also is one access point for the city's underground defensive labyrinth, the Casemates du Bock, dug into the rock below the city in 1745. At the entrance, the Archaeological Crypt provides an excellent introduction, with an audiovisual presentation depicting Luxembourg history from the 10th to the 15th centuries.