Bergen-Belsen, sometimes referred to as just Belsen, was a German concentration camp in the Nazi era. It was located in Lower Saxony, southwest of the town of Bergen near Celle.

It was started in 1940 as a POW camp. After 1941 about 20,000 Soviet soldiers were tortured and killed in the camp. Later (1942) Bergen-Belsen became a concentration camp; the SS took the command in April 1943. There were no gas chambers in Bergen-Belsen, since the mass murders took place in the camps further east; nevertheless thousands of Jews, homosexuals, and Roma and Sinti were tortured or starved to death. In 1945 the prisoners of other camps were brought to the front lines, since these camps were liberated by the Soviets. In overcrowded conditions disease and malnutrition caused many deaths. Mass graves were dug. When the British liberated the camp on April 15, 1945, they found thousands of bodies unburied. Bergen-Belsen was razed to the ground following the liberation because of the infestation of typhus and lice.

70,000 people died in Bergen-Belsen. Two of them were Anne Frank and her sister Margot, who died there in March 1945.