Alte Pathologie Wehnen, Memorial site in Bad Zwischenahn, Germany.

The Alte Pathologie Wehnen is a memorial and documentation center housed in the former pathology building on the grounds of the Karl-Jaspers-Klinik in Bad Zwischenahn-Wehnen. The building was made available to the Gedenkkreis Wehnen after 2002, and the association has since used it to inform visitors about the Nazi euthanasia crimes committed at the former Heil- und Pflegeanstalt Wehnen.

The Wehnen healing and care institution was long wrongly believed to have carried out no Nazi euthanasia. In fact, about three years before Action T4, patients were killed by starvation and probably medication; from 1939 overcrowding pushed the 400-bed facility to up to 1,200 patients. Around 1,500 patients were killed during the Nazi period, with deaths peaking in 1945 at six times the normal rate. Historian Ingo Harms's 1996 dissertation brought this to public attention.

The memorial was initiated and built by relatives: after historian Ingo Harms published his dissertation in 1996, families of patients who died in Wehnen founded the Gedenkkreis Wehnen e.V., which has held annual commemorations on 1 September since 2000, the date Hitler backdated the euthanasia order. On the Protestant cemetery in neighbouring Ofen, a white marble pillow on a thyme bed and 1,500 pebbles stand for the dead; relatives can have a stone engraved with a name.

The memorial rooms are in the former pathology building on the Karl-Jaspers-Klinik grounds in Wehnen; the Gedenkkreis Wehnen e.V. association, registered since 2003, runs the site and helps relatives research individual patient fates. Annual commemorations with lectures are held on 1 September, the date to which Hitler backdated the euthanasia order. The bronze memorial by Traudl Knöss stands on a lawn to the right of the main entrance, near the memorial rooms.

The memorial was initiated and built by relatives of victims, not by doctors or academics; nationwide Wehnen was the only Nazi euthanasia memorial created by such a family group. The Gedenkkreis Wehnen e.V., founded after Ingo Harms published his dissertation in 1996, was granted the vacant Old Pathology building after 2002.