Buchenwald was one of the first and the biggest concentration camps. It was built in 1937 in Weimar, Germany. It held 20,000 prisoners and most of them worked as slaves in near by factories. There were no gas chambers in Buchenwald, but many died from disease, little food or the wrong kind of food (malnutrition), exhaustion, beatings, and executions. Prisoners were used to test the viruses and their vaccines. Buchenwald first opened for male prisoners in July 1937. Women were not part of the Buchenwald camp system until 1944. Prisoners were confined in the northern part of the camp in an area known as the main camp, while SS guard barracks and the camp administration compound were located in the southern part. The main camp was surrounded by an electrified barbed-wire fence, watchtowers, and a chain of sentries outfitted with automatically activated machine guns. The jail, also known as the Bunker, was located at the entrance to the main camp. The SS carried out shootings in the stables and hangings in the crematorium area.Most of the early inmates at Buchenwald were political prisoners. However, in 1938, in the aftermath of Kristallnacht, German SS and police sent almost 10,000 Jews to Buchenwald where they were subjected to extraordinarily cruel treatment. 600 prisoners died between November 1938 and February 1939.