Majdanek :

Nazi camp and killing center opened for men and women near Lublin in eastern Poland in late 1941. At first a labor camp for Poles and a POW camp for Russians, it was classified as a concentration camp in April 1943. Like Auschwitz, it was also a major killing center. Majdonek was liberated by the Red Army in July 1944, and a memorial was opened there in November of that year.