An impressive vestige (43 000m²) from the Second World War, this submarine base was built from 1941 to 1943 to house the German Navy's 12th submarine flotilla. It is now an underground cultural centre, hosting temporary exhibitions of contemporary art and concerts. The Bassins de Lumières exhibition projects artistic works onto its walls. Their reflection in the waters of the basins provides visitors with a fascinating and immersive digital experience.