Warburger Straße / Peter-Hille-Weg retention basin, excavated by Jewish camp inmates of the so-called "Grüner Weg" Jewish retraining camp.

In 1941, the city of Paderborn had underground reservoirs and open ponds built as part of preventive air-raid protection measures. These included the Warburger Straße / Peter-Hille-Weg pond, which was also designed as a retention basin for rainwater. It was dug by the inmates of the so-called retraining camp „Grüner Weg“. See also "Das jüdische Umschulungs- und Einsatzlager Grüner Weg"  in the category "Bildung". 

This camp was set up in July 1939 at Grünen Weg 86 (corner of Frankfurter Weg). The land had been made available free of charge by the city of Paderborn to the "Reich Representation of German Jews" so that young Jews (men and women) could be trained in physical, mainly agricultural and horticultural work in preparation for their emigration as part of Jewish self-help. The retraining camp, which was in fact more of a labor camp, was under the control of a Jewish director in internal camp matters. The deployment of labor was determined by the head of the municipal vehicle fleet in the municipal companies: mainly in refuse collection, street and sewer cleaning, road and ditch repair and the maintenance of municipal green spaces and cemeteries, but also in Paderborn businesses and for unloading wagons at the freight station. Around one hundred young Jews lived in the camp. Their length of stay was subject to fluctuations. Some of the camp inmates were still able to emigrate. However, with effect from October 23, 1941, Reichsführer SS Heinrich Himmler prohibited all Jewish emigration. While the first deportation of Jewish citizens from Paderborn to the Riga ghetto began on December 10, 1941, the labor of most of the Jews in the camp was still needed to carry out tasks important to the war effort. Of the camp inmates, only twelve men and one woman survived Auschwitz and other concentration camps after the evacuation of the camp and deportations.