Auschwitz was probably chosen to play a central role in the “final solution” because it was located at a railway junction with 44 parallel tracks—rail lines that were used to transport Jews from throughout Europe to their death. Heinrich Himmler, chief of the SS, the Nazi paramilitary corps, ordered the establishment of the first camp, the prison camp, on April 27, 1940, and the first transport of Polish political prisoners arrived on June 14. This small camp, Auschwitz I, was reserved throughout its history for political prisoners, mainly Poles and Germans.
In October 1941, work began on Auschwitz II, or Birkenau, located outside the nearby village of Brzezinka. There the SS later developed a huge concentration camp and extermination complex that included some 300 prison barracks; four large so-called Badeanstalten (German: “bathhouses”), in which prisoners were gassed to death; Leichenkeller (“corpse cellars”), in which their bodies were stored; and Einäscherungsöfen (“cremating ovens”). Another camp (Buna-Monowitz), near the village of Dwory, later called Auschwitz III, became in May 1942 a slave-labour camp supplying workers for the nearby chemical and synthetic-rubber works of IG Farben. In addition, Auschwitz became the nexus of a complex of 45 smaller subcamps in the region, most of which housed slave labourers. During most of the period from 1940 to 1945, the commandant of the central Auschwitz camps was SS-Hauptsturmführer (Capt.) and ultimately SS-Obersturmbannführer (Lieut. Col.) Rudolf Franz Hoess (Höss).
The death camp and slave-labour camp were interrelated. Newly arrived prisoners at the death camp were divided in a process known as Selektion. The young and the able-bodied were sent to work. Young children and their mothers and the old and infirm were sent directly to the gas chambers. Thousands of prisoners were also selected by the camp doctor, Josef Mengele, for medical experiments. Auschwitz doctors tested methods of sterilization on the prisoners, using massive doses of radiation, uterine injections, and other barbaric procedures. Experiments involving the killing of twins, upon whom autopsies were performed, were meant to provide information that would supposedly lead to the rapid expansion of the “Aryan race.”