These defensive works date back to 1644 when earlier fortifications were extended by the Spanish who were then occupying the territory. The layout today reflects further works by the famous French Architect. The Austrians in turn made their mark and in 1745 aadded the 54 gun emplacements. One of the nicknames of Luxembourg at this time was ‘The Gibraltar of the North’.
The defences fell into slow disrepair until the 1867 London Treaty (which established Luxembourg’s independence) stipulated that they be taken out of action. Public visits to the extensive network started in 1933 and the defences now form part of a World Heritage Site.