The Casemates of Luxembourg City
the first underground tunnels were built in 1644, in the era of Spanish domination. The 23-kilometre-long galleries were enlarged forty years later by French military engineer and fortress builder Vauban, then again in the 18th century by the Austrians. The subterranean defensive passages were placed on different levels and reached down as far as 40 metres. The casemates helped forge Luxembourg's impressive military reputation and it became also known as Gibraltar of the North. After the dismantling of the fortress in 1867, 17 kilometres of the casemates were spared and left in good condition. The Casemates du Bock and the Casemates de la Pétrusse have been open to the public since 1933. Luxembourg's fortifications and its old town, which is no less steeped in history, enjoy worldwide renown and have been designated a UNESCO World Heritage Site in 1994.