An inmate's first encounter with the camp, if they were being registered and not sent straight to the gas chamber, would be at the prisoner reception centre, where they were tattooed, shaved, disinfected, and given their striped prison uniform. Built between 1942 and 1944, the center contained a bathhouse, laundry, and 19 gas chambers for delousing clothes. Debórah Dwork and Robert Jan van Pelt write that inmates would then leave this area via a porch that faced the gate with the Arbeit macht frei sign. The prisoner reception center of Auschwitz I became the visitor reception center of the Auschwitz-Birkenau Memorial and Museum.
Birkenau was the largest camp in the Auschwitz complex. It became primarily a centre for the mass murder of Jews brought there for extermination, and of Roma and Sinti prisoners during its final period. Sick prisoners and those selected for death from the whole Auschwitz complex – and, to a smaller extent, from other camps – were also gathered and systematically killed here. It ultimately became a place for the concentration of prisoners before they were transferred inside the Third Reich to work for German industry. Most of the victims of the Auschwitz complex, probably about 90%, were killed in the Birkenau camp.
On November 12, 1938, Field Marshal Hermann Göring convened a meeting of Nazi officials to discuss the damage to the German economy from pogroms. The Jewish community was fined one billion Reichsmarks. Moreover, Jews were made responsible for cleaning up the damage. German Jews, but not foreign Jews, were barred from collecting insurance. In addition, Jews were soon denied entry to theatres, forced to travel in separate compartments on trains, and excluded from German schools. These new restrictions were added to earlier prohibitions, such as those barring Jews from earning university degrees, from owning businesses, or from practicing law or medicine in the service of non-Jews. The Nazis would continue to confiscate Jewish property in a program called “Aryanization.” Göring concluded the November meeting with a note of irony: “I would not like to be a Jew in Germany!”
Auschwitz inmates began working at the plant, known as Buna Werke and IG Auschwitz, in April 1941, and demolishing houses in Monowitz to make way for it. By May, because of a shortage of trucks, several hundred of them were rising at 3 am to walk there twice a day from Auschwitz I. Anticipating that a long line of exhausted inmates walking through the town of Oświęcim might harm German-Polish relations, the inmates were told to shave daily, make sure they were clean, and sing as they walked. From late July they were taken there by train on freight wagons. Because of the difficulty of moving them, including during the winter, IG Farben decided to build a camp at the plant. The first inmates moved there on 30 October 1942. Known as KL Auschwitz III-Aussenlager (Auschwitz III-subcamps), and later as Monowitz concentration camp, it was the first concentration camp to be financed and built by private industry.