51°13′14″N 22°35′58″E / 51.22056°N 22.59944°E / 51.22056; 22.59944

Majdanek (or Lublin) was a Nazi concentration and extermination camp built and operated by the SS on the outskirts of the city of Lublin during the German occupation of Poland in World War II. It had three gas chambers, two wooden gallows, and some 227 structures in all, placing it among the largest of Nazi concentration camps. Although initially intended for forced labor rather than extermination, it was used to murder an estimated 78,000 people during Operation Reinhard, the German plan to murder all Polish Jews within their own occupied homeland. In operation from 1 October 1941 to 22 July 1944, it was captured nearly intact. The rapid advance of the Soviet Red Army during Operation Bagration prevented the SS from destroying most of its infrastructure, and Deputy Camp Commandant Anton Thernes failed to remove the most incriminating evidence of war crimes.

The camp was nicknamed Majdanek ("little Majdan") in 1941 by local residents, as it was adjacent to the Lublin ghetto of Majdan Tatarski. Nazi documents initially described the site as a POW camp of the Waffen-SS, based on how it was funded and operated. It was renamed by the Reich Security Main Office as Konzentrationslager Lublin on April 9, 1943, but the local Polish name remained more popular.

After the camp's liberation in July 1944, the site was formally protected by the Soviet Union. By autumn, with the war still raging, it had been preserved as a museum. The crematorium ovens and gas chambers were largely intact, serving as some of the best examples of the genocidal policy of Nazi Germany. The site was given national designation in 1965. Today, the Majdanek State Museum is a Holocaust memorial museum and education centre devoted entirely to the memory of atrocities committed in the network of concentration, slave-labor, and extermination camps and sub-camps of KL Lublin. It houses a permanent collection of rare artifacts, archival photographs, and testimony.

Konzentrationslager Lublin was established in October 1941 on the orders of Reichsführer-SS Heinrich Himmler, forwarded to Odilo Globocnik soon after Himmler's visit to Lublin on 17–20 July 1941 in the course of Operation Barbarossa, the German invasion of the Soviet Union. The original plan drafted by Himmler was for the camp to hold at least 25,000 POWs.

After large numbers of Soviet prisoners-of-war were captured during the Battle of Kiev, the projected camp capacity was subsequently increased to 50,000. Construction for that many began on October 1, 1941 (as it did also in Auschwitz-Birkenau, which had received the same order). In early November, the plans were extended to allow for 125,000 inmates and in December to 150,000. It was further increased in March 1942 to allow for 250,000 Soviet prisoners of war.

Construction began with 150 Jewish forced laborers from one of Globocnik's Lublin camps, to which the prisoners returned each night. Later the workforce included 2,000 Red Army POWs, who had to survive extreme conditions, including sleeping out in the open. By mid-November, only 500 of them were still alive, of whom at least 30% were incapable of further labor. In mid-December, barracks for 20,000 were ready when a typhus epidemic broke out, and by January 1942 all the slave laborers – POWs as well as Polish Jews – were dead. All work ceased until March 1942, when new prisoners arrived. Although the camp did eventually have the capacity to hold approximately 50,000 prisoners, it did not grow significantly beyond that size.^{[citation needed]}

In July 1942, Himmler visited Belzec, Sobibor, and Treblinka, the three secret extermination camps built specifically for Operation Reinhard to eliminate Polish Jewry. These camps had begun operations in March, May, and July 1942, respectively. Subsequently, Himmler issued an order that the deportations of Jews to the camps from the five districts of occupied Poland, which constituted the Nazi Generalgouvernement, be completed by the end of 1942.