Auschwitz concentration camp was a complex of over 40 concentration and extermination camps operated by Nazi Germany in occupied Poland (in a portion annexed into Germany in 1939) during World War II and the Holocaust. It consisted of Auschwitz I, the main camp (Stammlager) in Oświęcim; Auschwitz II-Birkenau, a concentration and extermination camp with gas chambers; Auschwitz III-Monowitz, a labour camp for the chemical conglomerate IG Farben; and dozens of subcamps. The camps became a major site of the Nazis' Final Solution to the Jewish question.
https://en.wikipedia.org/wiki/Auschwitz_concentration_camp