More than one million people, mainly Jews, were killed at Auschwitz-Birkenau, Nazi Germany’s largest concentration camp in Poland, between 1940 and 1945.
A group of survivors will take part in a ceremony marking the 75th year since the Soviet army liberated it from the Nazis, but that number is dwindling year after year.
The survivors’ message is clear, that the world should not allow this to happen again.
Al Jazeera’s Jonah Hull reports from the Auschwitz-Birkenau concentration camp, Poland.