I've been an anti-death penalty campaigner for decades. But when I clapped eyes upon the gallows in Auschwitz I, I smiled.

This instrument of death, standing solitary close to the infamous Arbeit Macht Frei gates, had been used to execute Rudolf Höss, instigator, designer and over-seer of all that I'd just surveyed.

It's amazing how quickly a mind can turn to violence, and even slaughter, in such surroundings. Mine too, though I thought myself so immune to such sentiments. Peace campaigner, anti-Nazi protestor, Holocaust historian and Amnesty International activist that I am. Yet for the briefest moment there, I wanted that man dead. I wanted him to have suffered.

The gallows, it turned out, was a replica of the original. Though it stood on the same spot. Little else there had been thus recreated.

I'd walked inside buildings which had witnessed scenes of incomparable deprivation, starvation, torture, human experimentation and death. I'd seen the larger gallows in the parade grounds, where dozens at a time had hanged as a warning to others to comply. I'd been in the prison block, where cruel execution methods weren't so swift. I was about to stand inside a gas chamber and see the claw marks on the wall. Then face the last standing crematorium, where hundreds could be reduced to ashes each day.

This was only Auschwitz I. A short distance away, Auschwitz II (aka Auschwitz-Birkenau) would make the former look like a holiday camp. Bigger, more industrial sized killing complexes reduced to rumble as fleeing Nazis sought unsuccessfully to destroy the evidence.

SS-Obersturmbannführer Rudolf Höss - the man I'd smiled to know was killed - had done his job well. He'd come up with ideas on how to enact his orders to exterminate those deemed undesirable to the Third Reich. He'd traveled around concentration camps, gaining evidence, data and input from other officials, before delegating project teams to test his procedures for mass murder. Refining his methods; making the business of genocide ever larger, faster, more efficient.

So good at pursuing what he saw as his duty that Rudolf Höss had been made Commandant of Auschwitz, in order to put his designs into practice. His proposed operation made reality turned the ever expanding complex into the most notorious of all Nazi death camps.