On Sunday, 75 years ago the Germans blew up Crematorium V, the last of the five joint furnace/gas chamber complexes they had used so monstrously at Auschwitz.

With the arrival of the Russian Army imminent, they were trying to destroy evidence of the crime they had committed at this, the most notorious of the mass murder camps, the Holocaust’s heart of darkness.

Over the course of the war 1.1 million people – more than 90 per cent of them Jews – were murdered at Auschwitz.

That’s more than Britain and America’s combined number of war dead.

Auschwitz is situated in southern Poland's barren flat land. Credit: ITV News

Auschwitz stretches across more than 400 acres of bleak flat land in southern Poland.

There’s a stark nothingness about much of it.

The people murdered here were wiped off the face of the earth.

There’s no record of who they were; they have no graves; their ashes were dumped into ponds and rivers.

Holocaust survivor Hannah Lewis recalls her memories of Auschwitz and watching her mother being shot

That’s why the survivors are so important – witnesses to the greatest crime in history.

Inevitably their numbers are dwindling, but a few brave souls have summoned up the courage to return here and bear witness once more.

Theirs are the authentic voices of horror as the world remembers the 75th anniversary of Auschwitz’s liberation by the Russians.

Auschwitz's gas chambers where thousands of people were killed. Credit: ITV News

Artificial limbs that belonged to people brought to Auschwitz. Credit: ITV News

A total of 7,000 prisoners were liberated.

In anticipation, the Germans had moved another 60,000 westwards towards other camps. Many of them would die on Death Marches.

Almost half of the 7,000 people set free would also die. They were too ill, starving or exhausted to survive.

Drone footage of Auschwitz concentration camp

As the Auschwitz story begins to dip beyond the horizon of living memory questions are being asked about the future of remembrance as time moves on.

I would venture that this symbol of human depravity will always endure, as it should.

A place of unimaginable suffering inflicted by unfathomable cruelty – visitor numbers at Auschwitz have doubled over the last decade.