The Emanuel Ringelblum Jewish Historical Institute houses the largest archival collection related to the Jewish presence in Polish lands over the last 1,000 years. Its most precious holding is the remnants of the Warsaw ghetto’s underground archive, collected by Emanuel Ringelblum and the Oneg Shabbat group. For Yerusha, the Institute carried out a pilot project to map Poland’s vast Jewish-related archival holdings which has served as the springboard for a larger survey carried out by the University of Wrocław’s Department of Jewish Studies.