The Castle can be visited
Grafeneck Castle

Grafeneck Castle, a historic building near Gomadingen in the district of Reutlingen, Baden-Württemberg, was originally built as a hunting lodge. It developed into a baroque residence and later into a place of remembrance for the atrocities of National Socialism.
History+
The origins of Grafeneck Castle lie in a high medieval fortress. Around 1560, the Dukes of Württemberg had a hunting lodge built on this site. Duke Carl Eugen of Württemberg used the estate as a summer residence and expanded it between 1762 and 1772 into a baroque castle with an opera house and numerous pleasure buildings. The opera house was later moved to Ludwigsburg, and the castle was abandoned. In the 19th century, parts of the castle were demolished and it served the forestry office. In 1928, the Samaritan Foundation acquired the castle and established a home for people with disabilities, including its own cemetery from 1930. During the National Socialist era, Grafeneck was confiscated in October 1939 and converted into an extermination center.
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 48.3927, 9.4295