The Castle can be visited
Scharfenstein Castle

Scharfenstein Castle, a High Middle Ages complex in the Eichsfeld region of Thuringia, was first documented in 1209. It stands on a mountain spur.
History+
The construction of Scharfenstein Castle is presumed to have taken place in the second half of the 12th century, although a Godehard von Scharfenstein was mentioned as early as 1161. In the early 13th century, while owned by the Counts of Gleichenstein, it underwent expansion. A feud between the Archbishop of Mainz and the Landgrave of Thuringia led to the castle's conquest and destruction by Ludwig IV in 1219. By the mid-13th century, it was rebuilt with an extended curtain wall. In 1294, the heavily indebted Counts of Gleichenstein sold the castle to Archbishop Gerhard II von Eppstein of Mainz, marking the beginning of Mainz's rule over Eichsfeld. In the 14th century, Scharfenstein served as a pledge office until it belonged to the Lords of Wintzingerode in the 15th and 16th centuries. A lightning strike almost completely destroyed the castle in 1431, but it was rebuilt. During the Peasants' War in 1525, the castle was again plundered under the leadership of Heinrich Pfeiffer, but restored seven years later by Friedrich von Wintzingerode.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=2036
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: 51.3633, 10.2689