During the Nazi occupation of Ostrowiec, the Gestapo Headquarters and jail was at a building in current day 63 Henryka Sienkiewicza . (Stanislaw Witczak before his passing even showed some people the "jails" that were still evident in the basement of the home.  The SS Living quarters were located on current address 2 Sławomira Czerwińskiego. In the testimony linked here, Asher Rubinstein describes his experience in these buildings.