Hartheim Castle, a Renaissance structure built in 1600 in Alkoven near Linz, stands as a significant historical memorial site. Originally converted into a care facility in the early 1900s, the castle became one of six Nazi euthanasia centers during World War II. Today it operates as the Memorial Site Hartheim Castle, dedicated to preserving the memory of approximately 30,000 victims. Visitors can explore the original rooms where crimes occurred, visit exhibitions such as "Wert des Lebens," and access research materials at the Hartheim Documentation Center. The site offers guided tours and educational programs for groups and individuals seeking to understand this dark chapter of history.