The first prisoners arrived at the newly established Ravensbrück women's concentration camp in May 1939. The concentration camp was located close to the town of Fürstenberg, north of Berlin. Medical experiments were carried out on the prisoners in the so-called sick barracks. The concentration camp also served as a training site for female guards. After several weeks of training, they were usually sent to other camps. In 1945, between 20,000 and 30,000 women were imprisoned in the Ravensbrück concentration camp. Shortly before the war ended, the rise in the number of inmates was so dramatic that up to six women had to share a single bed.