Sonnenburg concentration camp
Gmina Słońsk, Poland
The Sonnenburg concentration camp (Konzentrationslager Sonnenburg) was a Nazi German concentration camp, that was opened on 3 April 1933 in Sonnenburg (now Słońsk in Poland) in a former prison, on the initiative of the Free State of Prussia Ministry of the Interior and Justice.
Prison data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).