Two tonnes of human hair piled into a macabre haystack - you can still see the pigtails hacked from the heads of the child victims.
A room full of pots and pans, a room full of suitcases - all with the names of the victim written on the sides.
A child’s doll, its head smashed in under the weight of a boot . . . perhaps.
Shoes - thousands and thousands of shoes.
Thousands of razors and combs, thousands of pairs of spectacles.
A set of keys.
These are some of the relics left behind by the million-plus people killed at Auschwitz-Birkenua between 1940 and 1945.
Bearing witness - that is why we are here.
And what is as memorable as the hair, the pots and pans, and the suitcases - is the grooves worn in the stone stairs in the barrack rooms at Auschwitz I.
Since the end of the Second World War, since the site on the outskirts of the Polish city of Krakow was turned into a museum in 1947, hundreds of thousands, millions probably, have climbed these stairs.
They have come to see.
They have come to bear witness.
I have come on this visit at the invitation of the Holocaust Educational Trust as part of its ‘Lessons from Auschwitz’ programme, along with hundreds of young people from around Nottinghamshire and Derbyshire.
Now in its seventeenth year, the project is based on the premise that “hearing is not like seeing” - that the only way of keeping the horrors of the Holocaust alive is if people come, and see, and bear witness.
And you do need to see it.
Towards the end of the tour, as we are standing next to the wrecked gas chambers that the Nazis managed to destroy as the Red Army advanced on the camp, the light just going, our tour guide says something profound.
“The witnesses that are left now, the last surviving victims are all in their late 80s and 90s now,” she says. “Soon this place will be the only witness. I believe this place is a huge cemetery, albeit a cemetery without any bodies.”
And that is why you need to go - because unless you go you simply cannot understand the scale of the operation the German SS built there - an industrial killing machine, designed to wipe a race of people from the face of the earth.
Our educator Steve Richardson, a teacher based in the Amber Valley area, asks the students in our group why they think the Germans tried to destroy the camps before the Russian Army arrived?
Did they realise, at the bitter end, that they had been wrong? Was it guilt? Or where they just trying to hide their crimes, to cover their tracks?
But a huge amount of evidence has been destroyed - the gas chambers at Birkenau, which were the locations of 90 per cent of the murders, are now just blown-out craters in the earth.
The ‘Canada huts’, where the victims possessions were pilfered for gold and valuables, were destroyed as well.
The scale of Auschwitz is so vast, that their was no chance that the Nazis could fully cover their traces. Not altogether.
From the main gates at Birkenau it is a 20 minute walk over rough ground to the site of the chambers - a further 10 minutes of hard walking to the processing block, where those assigned to live were ‘taken’.
Auschwitz II (Birkenau) is as big as a large town, or small city. It is as big as Mansfield. It is as big as Chesterfield. It is as big as Derby city centre. They had to clear out five whole villages to create it.
They only built it when Auschwitz I was at capacity - when they realised that the gas chambers there were not up to the task of carrying out Hitler’s ‘Final Solution’.
But there is more - around 40 sub-camps in total in the Auschwitz area which fed into the main camp, and the problem with setting up such a place of Hell, is that it becomes very difficult to wipe it from the face of the earth.
They tried very hard.
The ashes of the victims were routinely disposed on in a nearby river, but the Nazis did not have the time to dispose of them all.
There are pits in the Birkenau site, the principal extermination camp, that were found with mounds of human ashes at the bottom. This place remains their grave.
It is also the grave for many thousands whose only trace is a shoe, a pan, a pair of spectacles, a house key.
Some managed to leave letters, documenting what happened to them, but the vast majority left nothing - not even a name.
Those assigned for ‘special treatment’ were not even registered. They could be off the train and into the chamber within half an hour - their names erased along with their bodies.
The museum states that the 1.1 million figure is a conservative estimate.
Richard tells the students that it is vital that we ‘re-humanise’ the victims - to find commonality with them. But it is also vital that we re-humanise the perpetrators, he says, and the bystanders - the majority, who turned a blind eye to genocide.
Names on suitcases - the names of people who thought they would be reclaiming their possessions.
House keys - belonging to someone who had locked their house and brought the keys with them, one day expecting to return.
The students look at photographs.
Some are taken from albums - of families and children and young couples, before their lives were swept away in a hurricane of lunacy.
Others are prisoner faces - of those selected to live.
Under their faces, some of which are almost smiling, there is their date of birth, their date of death, and their date of arrival at the camps.
Few survived more than a few months, even the young, the strong and the fit.
Before we visit the camps, we go to the town of Oświęcim - the town that was renamed Auschwitz by the Third Reich.
We look in the Jewish cemetery which dates from before the Holocaust, from a time when more than one in two people in the town were Jewish.
Today, there are no Jews in Oświęcim. They have all gone, but we are reminded of a community that had thrived in this place - living with integrity and dying with dignity for many hundreds of years.
The day concludes with a candle-lit service, led by London-based Rabbi Andrew Shaw.
He describes the story of his own grandparents - him vanishing without a trace when he was expelled from Austria by the Nazis, her escaping, unknowingly pregnant, to Glasgow.
He tells their story to the students as it was told to him.
But this is just one story,” he says, “just one amongst millions”.
And he passes on the story to today’s young people so they can bear witness, just like the neglected graves in the Jewish cemetery do, and the grooves worn into the staircases from the millions of trampling feet.
Images (c) Holocaust Educational Trust