Auschwitz
Established within disused army barracks in 1940, Auschwitz was initially designed to hold Polish prisoners, but was expanded into the largest centre for the extermination of European Jews. Two more camps were subsequently established: Birkenau and Monowitz. In the course of their operation, between one and 1.5 million people were killed. Auschwitz was only partially destroyed by the fleeing Nazis, so many of the original buildings remain as a bleak document of the camp's history.