The Lajkonik bus leaves Kraków Central Bus station (usually from the upstairs "G" bays, instead of the downstairs "D" bays). Some busses go directly to Auschwitz, after passing the Oświęcim train station (OŚWIĘCIM, Dworzec PKP): they usually say "Oświęcim, Auschwitz Museum". The trip takes about 90 minutes, but beware some routes take much longer (e.g. 2h30m).
Heinrich Himmler's Schutzstaffel (SS) took full control of the police and the concentration camps throughout Germany in 1934–35. Himmler expanded the role of the camps to hold so-called "racially undesirable elements", such as Jews, Gypsies/Romanis/Sintis, Serbs, Poles, disabled people, and criminals. The number of people in the camps, which had fallen to 7,500, grew again to 21,000 by the start of World War II and peaked at 715,000 in January 1945.