Parks and gardens of psychiatric hospitals in the late 19th and early 20th centuries are a particular example of garden design art and testify to the role of designed landscape in therapy. Along with the evolution of psychiatry within the last 100 years, institutions for neurotic and mental patients have evolved too. Besides being adapted for contemporary purposes, hospital gardens have also become sites of commemoration of the victims of Nazi euthanasia of psychiatric patients, perpetrated during the Second World War. This article describes selected Aktion T4 memorials in their park and garden landscape context.