Schloss Hartheim, also known as Hartheim Castle, is a castle at Alkoven in Upper Austria, some from Linz, Austria. It was built by Jakob von Aspen in 1600, and it is a prominent Renaissance castle in the country. The building became notorious as one of the centers for the Nazi killing program known as Action T4, in which German citizens deemed mentally or physically unfit were systematically killed with poison gas. After the end of Action T4 (August 1941), these killings were extended to include Jews, Communists and others considered undesirable by the state who were imprisoned in concentration camps. These people stem from various countries in the world. In this capacity it was known as the Hartheim Killing Facility. In sum 30.000 people (18.000 people with handicaps and mentally ill people, about 12.000 concentrations camp prisoners and forced laborers) were killed in Hartheim until the end of the year 1944. In 1898, Prince Camillo Heinrich Starhemberg (1835–1900) donated the castle as a gift to the Upper Austria Charity Organization. With the help of additional donations, they used the castle from the beginning of the 20th century as a psychiatric institution (German: Psychiatrische Anstalt, but originally called the Idioten-Anstalt). History to 1940 Hartheim lies in the middle of the so-called Eferding Basin, that runs along the River Danube from Ottensheim to Aschach an der Donau. As early as 1130, a family with the name Hartheim is mentioned in the records. They were vassals of the bishops of Passau. In 1287, three brothers, Conrad, Peter and Henry of Hartheim, were named as owners of the castle as part of a barter arrangement with the Wilhering Abbey. In any case by 1323, another family was named as the owners. Until the middle of the 14th century the site consisted mainly of just one tower, subsequently a residence was added and it was surrounded by a small wall with ramparts and ditches. After changing hands several times the castle ended up in the possession of the Aspen family, who probably built the castle into its present shape. At the beginning of the 1690s they had a completely new castle built conforming to perceptions of the ideal Renaissance style with a regular four-winged building with four polygonal corner towers and a higher central tower. In 1799, George Adam, Prince of Starhemberg, purchased the castle. However, by 1862 the castle was in a rather poor