Fortress of Luxembourg

The site comprises a network of defensive structures with bastions, walls, and towers distributed across multiple levels of Luxembourg City's plateau. The architecture integrates natural rock formations and connects aboveground fortifications with an extensive system of underground passages carved into the sandstone cliffs.

The fortification developed over nine centuries into one of Europe's strongest strongholds, with successive rulers from Spain, France, Austria, and Prussia expanding and modernizing the defenses. The Treaty of London in 1867 mandated the dismantling of military structures when Luxembourg gained neutral status, leaving only a portion of the original complex intact.

The remaining fortifications document the city's strategic importance as a military stronghold in central Europe and now serve as an educational center for visitors studying European defense systems. The fortress remains have become a symbol of Luxembourg's transition from military stronghold to neutral nation.

Access to the fortress grounds is available during day and night hours, with guided tours offered to explore the underground passages and military architecture. The casemates require an admission fee and provide informational materials in multiple languages, while portions of the aboveground fortifications are freely accessible.

The complex spans three distinct levels and incorporates natural cliff faces as part of the defensive system, while 23 kilometers (14 miles) of underground galleries housed barracks, kitchens, bakeries, and storage rooms for up to 1,200 soldiers. These underground spaces also provided stabling for horses and featured sophisticated ventilation systems.