Asseburg

Asseburg - Credit: Wikimedia Commons

The Asseburg is a ruined hill castle on the narrow, southern crest of the Asse ridge in the Harz Mountains of Germany, not far from Wolfenbüttel. The castle was built around 1218 by Gunzelin of Wolfenbüttel and his descendants of the House of Asseburg, as a so-called Ganerbenburg, or castle managed and occupied by more than one family or branch. Based on its dimensions, this elongated fortification was the largest hill castle in North Germany and was considered impregnable. Its purpose was to secure the lands around Wolfenbüttel. Read more on Wikipedia

type: military installation
date from: 1218

Source: en.wikipedia.org