About 18 million people passed through the Nazi concentration camps during WWII, a fifth of them children.

Anatoly was just 11 when he found himself in the camp. Death and brutality was all around, and he says he feels lucky to be alive.

”If anyone fell while working, the overseers killed him or her,” Anatoly remembers.

“And they tried to spare each round of ammo. The Nazis got a glass of vodka for saving a round and killing someone with a shovel."

Before being killed, people were exploited until their last breath. Even after their death, prisoners continued bringing profit as their hair, ashes, and bones were used in manufacturing.

When Ekaterina Speranskaya was taken to the camp, she knew nothing about its terrors. But she says she was fortunate to meet wise people who taught her how to survive:

”I was told: Say you haven’t seen anything, haven’t heard anything, and don’t know anything. Pretend that you’re dumb. And never show them your tears. If they beat you, never cry. If they see you crying, they only beat you harder, and then they throw you into a gas chamber."

Ekaterina says she’ll never forget the day of liberation. When the Nazis realized that the occupied territory could be freed soon, they organized what were known as “death marches," forcing prisoners away from the liberators.

“They lined us up and drove us on. The jailers had dogs and rode horses,” Speranskaya recalls.

“If you fell down on the way, and couldn’t get up, they shot you right on the spot. I was ready to collapse, I couldn’t take it anymore. And then we heard someone shouting: ‘Don’t stand there like you’re made of stone, people! The Nazis are gone!’ There was a thick morning fog that day, and we hadn’t noticed they were gone – we had plodded on, staring into the ground. And then, suddenly, we saw Soviet tanks coming towards us!”

By May 1945, the majority of the Nazi camps were liberated. It was only afterwards that the world realized what was happening behind its barbed wire fences.

Half a century later, monuments to the victims of Nazi concentration camps have appeared all over the world, dozens of museums have been built on sites where prisoners were held. The aim is to make sure people always remember the horrors of the fascist regime and its deadly ideology. But as the living survivors die out, the task becomes harder. Some fear Nazi ideas could once again re-capture people’s minds.