Hartheim Castle was the site of a Nazi euthanasia killing centre between 1940 and 1944. Up to 30,000 people were murdered there using carbon monoxide. These were about 18,000 people with mental illnesses or disabilities. From August 1941, the Nazis also murdered concentration camp prisoners and forced labourers in Hartheim. After 1945, Hartheim Castle served as a residential home. For decades, commemoration was mainly carried out by foreign organisations. In 1969, a first memorial room was set up. After many years of attempts, the Hartheim Castle Place of Learning and Remembrance was opened in 2003, which includes the memorial for Nazi victims and the exhibition “Value of Life”. Visitors can take advantage of educational offers. The documentation centre is available to researchers and victims’ relatives.