Buchenwald concentration camp
After the Allies won World War II, the Soviet Union took over Buchenwald and some other parts of Germany.  From 1945 to 1950, they used Buchenwald as an internment camp.  They called it NKVD Special Camp Number 2.  (The NKVD was the Soviet police organization that ran the camp.)  On January 6, 1950, the Soviets handed over Buchenwald to the East German Ministry of Internal Affairs.