The EL-DE House was named after its builder, the Cologne wholesaler of gold and watches Leopold Dahmen. From 1935 it served as residence for the Secret Police for the District of Cologne and was primarily spared of bombing damage during the War. Today it is the home of the Cologne NS Documentation Centre with various areas: the memorial "Gestapo Prison" in the cellar of the house is one of the best kept prisons of the NS times. More than 1,800 wall inscriptions tell of persecution, torture and murder. The NS Documentation Centre has been awarded several prizes, also internationally, for the permanent exhibition “Cologne in the times of National Socialism” and for the changing special exhibitions. In the documentation and research area the files, which were largely destroyed during and at the end of the War, are reconstructed meticulously.