The remains of the Castle can be visited
Heimburg Castle

The Heimburg Castle Ruin, also known as Altenburg, is a former hilltop castle located near Heimburg, a district of Blankenburg (Harz).
History+
The origins of Heimburg likely date back to around 1070, when Emperor Henry IV had it built as a bulwark against the Saxon princes. It was first documented in 1073. Following a feud with the Counts of Regenstein, the castle passed into their possession, after which a line of this noble family subsequently called themselves von Regenstein-Heimburg. In the 16th century, the castle was mortgaged multiple times.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Roland Neubert, Halle (Saale)
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: 51.8272, 10.9108