Often, the living suffered more.

The camp had various classes of prisoners. They were distinguished by special marks and numbers tattooed on flesh; Jews were treated the worst.

The inmates were treated worse than slaves. They toiled in the extreme Polish winter with little clothing, several slept on a hard wooden bunk. They were given little to eat. They were subjected to inhuman tortures as part of 'experiments'.

Disobedience was punished with starvation, hanging or shooting.

A sign in German warns of the high voltage in the now defunct electric fence at Auschwitz I.

Photograph: Sean Gallup/Getty Images