[SJackson]

Auschwitz was built where the Jews were, more accurately at it's inception, where the POWs and Polish political prisoners were.

[Petronski]

My understanding was that Auschwitz was built because of its a confluence of coal, fresh water and substantial rail access, to suit the designs both of RSHA and IG Farben.

[PzLdr]

Auschwitz was built where railroad lines intersected, where the area was sparsely populated [the camp was sited on an old cavalry installation], and where secrecy could me maintained; criteria that applied to all six death camps.

It was not sited “where the Jews were”, in the sense that Heydrich intended combing the Jews in Europe west to east, and concentrating them in ghettos prior to their extermination. In fact he constantly refused Hans Frank's demands that he kill the Jews in the Government-General first.