The “Bock” is a promontory in the north-eastern corner of Luxembourg City’s old historical district. Archaeological evidence shows that this natural defensive area was probably used as early as antiquity and early medieval times by the Romans and Franks.
As a natural fortification, its rocky cliffs tower above the River Alzette and for this reason, Count Sigefroy, decided to purchase the Bock and build his castle and fortress defenses upon it in 963. In this way he could provide protection for his properties. There was probably some sort of castle structure on-site before he built, but there remains no confirmed physical trace of that earlier structure.
The defensive caves accommodated 50 cannons and a garrison of 1,200 men. In addition, they had underground facilities for housing equipment and horses as well as workshops, kitchens, bakeries and slaughterhouses. These impressive facilities allowed the city defenders to hold out against the French for seven months during the French Revolution, gaining the Casemates the prestigious title of “best in the world apart from Gibraltar”
In more recent times, the Casemates again proved their worth during WWII, when they were used as a bomb shelter for up 35,000 people. Since 1933, the Casemates have been open to the public and in 1994, the caves became a UNESCO World Heritage Site.
The Bock and Casemates are definitely a "must see" when you visit