When Allied forces marched into the towns of Bergen and Belsen in the heart of Germany in 1945, there were few obvious signs of the atrocities they'd soon discover. As the forces moved in from the countryside, they passed tidy orchards and well-stocked farms. In a way, it was almost picturesque.
Then came the smell that would lead them to Bergen-Belsen, a concentration camp of 60,000 prisoners. Inside they found decaying bodies that numbered into the thousands. Men, women and children. For those still alive, there was no functioning water supply. Some had not been fed for days. Others were simply too ill to eat. The soldiers filmed what they witnessed, and in 1985 the grisly footage would form the basis for the documentary, Memory of the Camps, which aired again April 14, 2015 on FRONTLINE
Bergen-Belsen was only the beginning, though. In time, ghettos and camps would be discovered in Nazi-occupied territory throughout much of Europe. In all, at least 6 million people died in Nazi Germany's system of camps — more than 3 million were Jews.
The map is just a sliver of the reach of Germany's network of enslavement under the rule of Adolf Hitler from 1933 to 1945. Based on the work of historians at the Jack, Joseph and Morton Mandel Center for Advanced Holocaust Studies at the United States Holocaust Memorial Museum, it shows the locations (in grey) of 1,096 out of 1,150 ghettos they've identified in Nazi-occupied Eastern-Europe. The locations in black represent 868 of the 1,094 concentration camps they've documented. (Locations in yellow were filmed in Memory of the Camps.)