Survivors of the Holocaust visited the former Nazi death camp Auschwitz on Monday, a day ahead of ceremonies marking the 70th anniversary of its liberation.Those gathered in front of the gate with the inscription "Work sets you free", offering a false promise of freedom, are some of the last people left alive to tell their story.At a ceremony attended by heads of state on Tuesday, they will be delivering the speeches, but today they remain bitter that their voice is not heard."Some of the people still saying that it (the Holocaust) never happened. I'm here to tell the world it happened. And I'm strong enough, and I'm a victor. And the world has to learn from it and to live in peace," said survivor from Canada, Mordechai Ronen.He and almost 300 others have come to revisit the horrors of Auschwitz with one goal in mind - to keep its memory alive.Samuel Beller from the USA kept silent about what he saw in Auschwitz for forty years, until he learned of an attempt to trivialize the Holocaust."For forty years I did not open my mouth about what happened there. But after something happened, somebody told a girl in high school that you don't have to know about the Holocaust. So it got me very upset and I said 'why a girl, a Jewish girl should (not) know about these things?' I was very, very shook up. So, I started to go after this and ever since I don't stop talking about it," he said, no longer afraid to present his camp tattoo, a number given to every inmate stripped of their name and personality.The German occupiers built the Auschwitz camp in 1940 as a place of incarceration for the Polish prisoners. From 1942 it became the largest site of extermination for European Jews. In Auschwitz, Nazi Germany killed at least 1.1 million people, mainly Jews, but also Poles, Roma, Soviet prisoners of war and prisoners of other ethnicities including Germans.In Auschwitz and the nearby camp Auschwitz II - Birkenau, people were killed in gas chambers, their bodies later burned in crematoriums."The whole world, Europe is forgetting about the whole thing. They want to have proof - me, as proof, my son, as proof... they were killing people like nothing. It didn't mean anything. The smell was so bad here from burning people," recalls John Pekats.On January 27, 1945 the camp was liberated by the Red Army soldiers. Some 7000 sick prisoners including 130 children were found alive in the camp. From January 17 to 21, 1945 the Nazi's marched approximately 56,000 prisoners out of Auschwitz.These were, the so called, marches of death, where many prisoners were shot or died of exhaustion.