'I feel like crying': 85-year-old Holocaust survivor returns to Auschwitz

Zigi Shipper was just 14 when he arrived at this place of infamy. He’d spent days in a cattle truck so crowded there was only room to sit down once several passengers had died.

He was part of a transport of 500 prisoners who came to Auschwitz-Birkenau destined to work elsewhere. The fact that he was on this named list saved his life. Most of the other prisoners who arrived here never left.

I walked with this remarkable 85-year-old survivor through thick snow to a part of this vast camp he never saw as an inmate: the gas chambers where it’s estimated a million and a half men, women and children were exterminated.

“Do you know every time you talk about it I feel like crying how can you kill babies?” he asks.

It is the children’s execution that most disturb him, perhaps because he was a child himself when he arrived here.

We find a wall of photos snatched from inmates before their were sent to their deaths. Many are family portraits, the smiling faces of infants held proudly by their parents stare back at us.

Zigi is one of a dwindling number of survivors who is back to mark the 70th anniversary of the camp's liberation by Russian troops. Today several gathered under the gates, in tears at seeing those chilling words "Arbeit Macht Frei" (Work makes you free).

The heavy snow and biting cold adding to the bleakness of this monochrome landscape where so many died as part of the Nazis' Final Solution.

Zigi has devoted most of his life to telling others about what happened here.

“Why? Why? Why kill babies? Have we learnt? I don’t know, but we must not give up.”