Harzburg

The Harzburg, also called Große Harzburg, is a former imperial castle, situated on the northwestern edge of the Harz mountain range overlooking the spa resort of Bad Harzburg in Goslar District in the state of Lower Saxony, Germany. It was erected from 1065 to 1068 at the behest of King Henry IV of Germany, slighted during the Saxon Rebellion in 1073-75, and a century later rebuilt under Emperor Frederick Barbarossa and his Welf successor Otto IV, who died here in 1218.

Later used as a robber baron's lair, the hill castle crumbled into ruins over the centuries. Today it has almost completely disappeared; only fragments of the foundation walls and the towers together with the castle well are preserved.

Source: Wikipedia