Hartheim Euthanasia Center
(1940–1944)
By Or Shaked
Hartheim Castle, located in Alkoven near Linz, Austria, became one of Nazi Germany’s most deadly euthanasia centers during World War II. Originally a Renaissance castle, it was donated in 1898 to a charitable organization to serve as a care home for children with mental and physical disabilities, operated by the Merciful Sisters of St. Vincent de Paul.
After Austria’s annexation by Nazi Germany in 1938, the welfare society was dissolved, and the Nazi administration seized Hartheim. By early 1940, it was selected for conversion into a killing center under the so-called “Aktion T4” program, the Nazi regime’s systematic murder of individuals with disabilities. Chosen for its secluded location and existing infrastructure, Hartheim was transformed into a fully operational killing facility over a few weeks.
The first murders began in May 1940. “Aktion T4,” managed from Tiergartenstrasse 4 in Berlin, was driven by Nazi ideology rooted in eugenics and racial purity. Under the medical supervision of Dr. Rudolf Lonauer and his deputy Georg Renno, victims were murdered in a gas chamber disguised as a shower room, using carbon monoxide introduced from pressurized cylinders. The facility also included rooms for undressing, medical sham examinations, body storage, and cremation.
Victims were brought to Hartheim in sealed grey buses operated by the “Charitable Patient Transport Company” (Gekrat). During the official T4 period (May 1940–August 1941), around 18,000 people were killed, including those diagnosed with schizophrenia, epilepsy, dementia, or other chronic mental illnesses, as well as institutionalized individuals and children with disabilities. Selection decisions were based on questionnaires that evaluated productivity and family visitation factors. After death, victims’ gold teeth were extracted, and ashes were either scattered in rivers or randomly sent to families with forged death certificates. Brains were sent to researchers under the guise of scientific study.
The smell of burning flesh from the crematorium raised suspicions among locals, fueling rumors and resistance. Catholic Bishop Clemens August Graf von Galen’s widely circulated sermon condemning the killings contributed to the official halt of Aktion T4 in August 1941. However, the killings did not end.
From late 1941 through 1944, Hartheim continued operations under a follow-up initiative known as “Aktion 14f13,” which expanded the targets to include concentration camp inmates—primarily the sick, elderly, persons with disabilities, or those deemed “unfit to work.” Prisoners from Mauthausen, Dachau, Ravensbrück, and other concentration camps were murdered at Hartheim in the same manner as T4 victims. At least 12,000 more people were killed during this period, with some estimates for Aktion 14f13 victims reaching 9,000 or higher. In total, approximately 30,000 people were murdered at Hartheim, making it the deadliest of the six Nazi euthanasia centers.
Hartheim served as a proving ground for later genocidal actions, including the Holocaust. Personnel from Hartheim, such as Christian Wirth and Franz Stangl, went on to design and operate extermination camps in Poland as part of “Operation Reinhardt,” applying the same gassing and cremation techniques perfected at the euthanasia centers.
The final gassing at Hartheim occurred on December 11, 1944. In the months following, Nazi officials attempted to erase evidence of the atrocities. A group of prisoners from Mauthausen was brought in to dismantle the gas chamber and crematorium and return the castle to its prewar condition. The property was handed back to its former owners in early 1945.
After the war, Hartheim was used for temporary housing for refugees and flood victims, hindering early memorialization efforts. The first commemorative marker, placed in 1950 by a French survivor organization, stood outside the castle. In 1969, a formal memorial was created inside. The Castle Hartheim Association, founded in 1995, spearheaded efforts to turn the site into a center for remembrance and education. A modern memorial and museum opened in 2003, featuring artifacts, educational exhibitions, and excavated remnants of the gas chamber and victims’ possessions.
In December 2024, investigators uncovered a large mass grave near Hartheim Castle containing human ashes and bone fragments, confirming that not all remains had been destroyed or accounted for. The grave, about 460 to 490 square meters, is expected to be designated a war grave. Witnesses had testified that ashes were initially dumped in rivers but later buried on-site to avoid detection.
Today, Hartheim Castle stands as a solemn place of learning and reflection. Its legacy highlights the dangers of dehumanization and questions ideologies that measure human worth based on productivity or conformity.
Sources: “Euthanasia Centre 1940–1944,” Schloss Hartheim.
“Field Command Schloss Hartheim,” Mauthausen Guides.
“Hartheim,” Holocaust Historical Society.
“Tötungsanstalt Schloss Hartheim,” D-Day, Normandy and Beyond.
Matt Lebovic, “80 years ago, lethal Nazi T4 center began euthanizing Germans with disabilities,” Times of Israel, (May 9, 2020).
“Hartheim killing centre & Nazi euthanasia in “Upper Danube”. Historical reappraisal, documentation, education,” National Fund of the Republic of Austria for Victims of National Socialism, (June 28, 2021).
“Mass grave of Nazi victims found at Hartheim Castle in Austria,” Jerusalem Post, (March 18, 2025).
Jonathan Van Maren, “Grim Discovery at Nazi Euthanasia Site Reshapes Modern Debate,” European Conservative, (April 24, 2025).
Photo: Holocaust Encylopedia.
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