Oranienburg concentration camp (German: Konzentrationslager Oranienburg) was an early German concentration camp, one of the first detention facilities established by the Nazis in the state of Prussia when they gained power in 1933. It held the political opponents of German Nazism from the Berlin region, mostly members of the Communist Party of Germany and social-democrats, as well as a number of homosexual men and scores of the so-called undesirables.