Harzburg The Harzburg , also called Große Harzburg , is a former imperial castle on the edge of the Harz mountains directly above the spa resort of Bad Harzburg in Goslar district in the German state of Lower Saxony . The castle has almost completely disappeared ; only fragments of the foundation walls and the towers together with the well have survived . Location . The ruins of the " Große Harzburg " ( " Great Harz Castle " ) are located above the town in the Radau valley on the hill of the " Großer Burgberg " ( ) . It may be reached by the Burgberg Cable Car and has an outstanding view past the neighbouring summit of " Kleiner Burgberg " ( ) northwest over the northern Harz Foreland and , southwards , over the densely forested Harz . The remains of the castle on the " Großer Burgberg " are open to the public . In addition to a cafe its other points of interest are the 19 - metre high Canossa Column of 1877 and the Bismarck Elm in the castle grounds . It has two different keep s ; the square one has been partially rebuilt in modern times ( see photo ) . The layout of the castle and the remnants of the walls are explained on information boards at the site . One interesting feature is the wide ditch driven through the rock that separates the castle into an east and a west wings . To the north on the nearby hill of " Kleiner Burgberg " are the remains of the so - called " Kleine Harzburg " ( " Little Harz Castle " ) and to the east on the nearby Sachsenberg are the traces of a rampart , possibly constructed by the rebellious Saxons to besiege the " Große Harzburg " ( see below ) . The castle drew drinking water from the Sachsenbrunnen , a medieval spring in the woods . The water was piped over several hundred metres in wooden pipes . History . Under Henry IV . The " Große Harzburg " ( " Hartesburg " ) was erected during the castle building programme in Saxony from 1065 to 1068 and was strategically sited by King Henry IV . Henry ' s architect was later the Bishop of Osnabrück , Benno II . The castle provided protection for the nearby Imperial Palace of Goslar . Its walls extend right up to the steep face of the conical mountain top . At the time it was built the castle was impregnable . Despite its defensive strength , the castle was also especially palatial . For example , it contained , amongst other things , unusually large , three - roomed great hall and collegiate church , to which Henry had many relics transferred . He even had a sort of family vault built , in which he laid the bones of his brother , Conrad and his son , Henry , both of whom died young . At the start of the Saxon Rebellion in 1073 , Henry IV had to flee along with the imperial insignia from the Imperial Palace of Goslar into the Harzburg . The besieging force allegedly numbered 60 , 000 whilst his garrison only had 300 men . The king finally fled , according to legend , through the well of the besieged castle and a secret passage . In the Treaty of Gerstungen of 2 February 1074 , Henry was forced to agreed to slight his castles , including the Harzburg . He hesitated , however , and only had the walls and towers demolished , whilst the buildings themselves remained . But in the spring of 1074 the Harzburg was plundered by angry farmers in the area and completely destroyed . The collegiate church was not spared and the royal family tomb was desecrated . This gave Henry cause to advance with all his might against the rebellious Saxons again and so , on 9 June 1075 , the Saxons rebels were defeated at the First Battle of Langensalza . Under the Hohenstaufens and Welfs . Under Emperor Frederick I , the rebuilding work on the castle continued until 1180 and was completed by Emperor Otto IV , who died in 1218 at the castle itself . The Harzburg lost its immediate function as an imperial castle because Emperor Otto IV had to surrender the imperial regalia to the Hohenstaufens . However , in 1222 the Harzburg was awarded the title of " castrum imperiale " again , and the character of the castle as an imperial fortress remained largely intact up to the time it was pledged ( 1269 ) using the existing imperial enfeoffment of the Harzburg seat . Later history . This was followed by frequent changes of ownership . In the 15th century it was pledged as a fief to three brothers from Schwicheldt who turned it into a robber baron castle . The importance of the fort decreased steadily , resulting in its slow decline . A rebuilding of the castle in the 16th century was never carried out due to the high cost . During the Thirty Years ' War , the castle changed hands several times , although its complement remained intact . Since this type of fortification had become insignificant due to the changed nature of warfare , demolition of the remaining elements of the ruin began in 1650 . Since then the castle has amounted to little more than its foundation ruins and well . The urban settlement of " Neustadt " at the foot of the " Großer Burgberg " adopted the castle ' s name .