Bock Casemates
Ideal: Ideal for history, fortress architecture, underground tunnels, and city views.
Carving into the rock began in 1644 under the Spanish, then the French and Austrians expanded the system; total length once reached 23 kilometers, and 17 kilometers remain today. The defenses were so strong the city was called the Gibraltar of the North. The 1867 Treaty of London required the fortress to be dismantled, but blasting the tunnels would have collapsed the city above, so the entrances were sealed instead. During World War II 35,000 people sheltered here; the site joined the UNESCO list in 1994.
Did you know?
How long are the casemates?
The tunnel network cut into the rock once ran to 23 km; about 17 km survives today, with some sections descending seven levels deep.
What were the tunnels used for in wartime?
In the Second World War they served as civilian shelters for up to 35,000 people, and also held artillery positions, workshops and kitchens.
Why was the fortress demolished?
The 1867 Treaty of London guaranteed Luxembourg's neutrality on condition the fortress be dismantled. Demolition took 16 years, leaving only the underground casemates and some walls.
Why go?
- To see Luxembourg's UNESCO-listed defense tunnels
- To feel the city's fortress past and strategic position up close
- To view the Alzette Valley and old town from different angles
Travel tip
Some tunnel sections can be narrow and cool; comfortable shoes and a light layer help.
