In pictures: Auschwitz

Auschwitz expanded rapidly after the first camp, Auschwitz-I, was established in 1940, mainly as a penal colony.

The Nazis used the prisoners themselves to do the work of building two more camps.

Auschwitz-II was primarily a death camp, a key part of the Nazi plan to exterminate all Jews in Europe - the "Final Solution to the Jewish question".

Auschwitz-III was a forced labour camp supplying workers to the Buna rubber works.