The Underground Archive is the first attempt to document the Shoah from the perspective of those affected and directly during the events. Before World War II, Poland was home to 3.3 million Jews, and Warsaw was the cultural, religious and political center of this diverse community. A year after the German war of aggression began, the Nazis forced the Jewish population into a sealed-off part of the city. The historian Emanuel Ringelblum then stimulated an unprecedented project: a group working in secret, documenting the daily life of the ghetto under the code name Oneg Shabbat (Joy of Shabbat). Cut off from the world, it collected and produced a wealth of material. With the beginning of the systematic murder of Polish Jews, they unwillingly became chroniclers of the Shoah, which they themselves, with few exceptions, did not survive. After the war, a large part of the archive, buried in tin crates and milk cans, was recovered from under the ruins of the ghetto. With its approximately 35,000 preserved pages, it is now a UNESCO World Heritage Site. The volume is published on the occasion of the exhibition of the same name, which the NS Documentation Center Munich will open in cooperation with the Jewish Historical Institute Warsaw in June 2023.