The remains of the castle can be visited
CastleLangelsheim
Kansteinburg Castle
On the Kanstein near Langelsheim, the remains of the Kansteinburg, also known as Hindenburg, can be found. The vanished hilltop castle was built in Carolingian times and served as a staging post and refuge above the Innerste Valley on trade routes.
History+
The origins of the Kansteinburg date back to the 8th or 9th century, when it was built as a hilltop castle. Its location was at a ford of the "Alte Straße" or "Königsweg," which connected Hildesheim and Werla, as well as at the confluence with the Rennstieg from the Harz.
Image: http://de.wikipedia.org/wiki/Datei:Kanstein_Langelsheim_01.JPG
Location: 51.9404, 10.3495