Riese ([ˈʁiːzə] German for "giant") is the code name for a construction project of Nazi Germany in 1943–1945, consisting of seven underground structures located in the Owl Mountains and Książ Castle in Lower Silesia, which was in Germany but is now in Poland. None of them were finished, and all are in different states of completion with only a small few tunnels reinforced by concrete. The construction work was done by forced labourers, prisoners of war (POWs), and prisoners of concentration camps, and many lost their lives, mostly as a result of disease and malnutrition.