On 27 January 1945, soldiers of the Red Army, the military force of the Soviet Union, entered the Auschwitz concentration camp and the Birkenau extermination camp, in present-day Poland, as they advanced towards Berlin. It is Holocaust Remembrance Day. In these places, Soviet troops saw for the first time what the Allied countries — fighting against Nazi Germany during the Second World War — had only heard about in the preceding months. They discovered the Holocaust, the genocide perpetrated by the regime led by Austrian-born dictator Adolf Hitler and his henchmen against the Jewish population, the Roma people, and other minorities.

The gates of the Nazi concentration camp at Auschwitz. The inscription reads Arbeit Macht Frei, work sets you free © Keystone/Getty Images

A furnace at the Nazi concentration camp at Auschwitz © Gabriel Hackett/Getty Images

Jewish deportees wearing the Star of David at the Nazi concentration camp at Auschwitz © Hulton archive/Getty Images

Flowers left by visitors at Auschwitz in 1950 © Keystone/Getty Images

The Auschwitz concentration camp under snow in 1965 © Keystone/Getty Images

1945, German civilians view the atrocities committed at the Auschwitz concentration camp to learn the truth © Keystone/Getty Images

1940, a group of deportees arrives at the Nazi concentration camp at Auschwitz © Keystone/Getty Images

1955, beds where 4 or 5 people slept at the Nazi concentration camp at Auschwitz © Three Lions/Getty Images

How Holocaust Remembrance Day came about

Sixty years later, in 2005, the United Nations General Assembly chose 27 January as an international day of remembrance to commemorate the millions of victims of the Holocaust caused by Nazi fascism.

Resolution 60/7, adopted on 1 November 2005, rejects every form of denial — even partial — of the Holocaust as a historical event. It "unreservedly" condemns any manifestation of religious intolerance, harassment, incitement or violence against persons or communities that identify with a religious faith or an ethnic origin, whenever and wherever such acts may occur in the world.

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To this end, it calls on United Nations member states to develop educational programmes to instil the concept of remembrance and ensure that even the youngest generations can prevent a similar tragedy — a genocide — from ever happening again.