The Castle can be visited
Horneck Castle

In Gundelsheim am Neckar in the Heilbronn district, Baden-Württemberg, Horneck Castle stands, a structure approximately 177 meters above sea level. Originally a fortress of the Teutonic Order, it continues to shape the landscape and history of the region.
History+
The origins of Horneck Castle are not fully clear, but a mention of a Ludovicus de Horneck in 1238 suggests the Lords of Horneck as possible founders around 1200. Around 1250, Konrad von Horneck transferred the castle to the Teutonic Order and joined it, subsequently becoming the commander of the newly established Horneck commandry. The Teutonic Order extensively expanded and fortified the complex. In 1294, the Order acquired the remaining part of Gundelsheim. In the mid-14th century, old Gundelsheim was abandoned and rebuilt directly below the castle as a bailey, at which point the settlement received town rights. From 1438, after the loss of the Battle of Tannenberg, Horneck Castle became the nominal main residence of the Deutschmeister.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Bernd Walter
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: 49.2868, 9.1562