Seventy years ago this week, German authorities liquidated the Warsaw ghetto, a 1.3-square mile area sealed off from the rest of the city where authorities forced all of the city’s Jewish residents to live. At its peak, more than 400,000 Jews were crammed into the ghetto, living in squalid conditions with insufficient food rations. No more than 20,000 of them survived the Holocaust.

FRONTLINE filmmaker Marian Marzynski was one of the few. For two years, his family lived in the ghetto, where between 1940 and mid-1942, 83,000 Jews died of starvation and disease. In 1942, when German authorities began the mass deportations that sent about 265,000 Jews to the Treblinka death camp, Marzynski’s parents hatched a plan. A Christian family friend would take him in a carriage to the Christian side of Warsaw. He escaped, and not long after, his mother tried to join him.

German authorities returned to the ghetto in 1943 to send the remaining more than 55,000 residents to forced labor camps. But underground, armed units of residents fought the Germans off for more than a month in what would become known as the Warsaw Ghetto Uprising. The uprising ended on May 16, 1943, when German authorities succeeded in liquidating the ghetto; tens of thousands died in the uprising and German soldiers systematically burned building after building.

Today, the area sits four to five feet on top of the remnants and burnt debris of the ghetto. Marzynski journeyed back to the ghetto to explore the story of his childhood and those of other Jewish child survivors of the Holocaust. Walking through its haunted ground with his guide Kora, he recalls life growing up in the ghetto.

Not all of the Warsaw Ghetto was destroyed. Marzynski visits a tiny enclave of buildings that survived the war, imagining how the Jews living inside struggled to live.