The largest concentration and extermination camp established by Nazi Germany is situated in southern Poland, or modern-day Oświęcim. It was divided into three camps (forcible labor, extermination, and jail) and was founded in 1940, 1941 (Birkenau), and 1942. Jewish prisoners who were physically fit were transferred to a camp for slave labor, while the old, the frail, and the young and their mothers were put to death. Josef Mengele also performed medical experiments on a few of the inmates. As Soviet forces advanced in 1944–1945, the camp was progressively abandoned. Between 1.1 million and 1.5 million people are thought to have died in Auschwitz, with 90% of those slaughtered being Jews. Approximately 19,000 Roma (Gypsies), who were murdered in July 1944, and approximately 83,000 Poles are also thought to have perished. Later, a large portion of the camp was turned into a museum.