berg ▁( 2 5 5 . 9   m ▁above ▁N N ), ▁the ▁highest ▁point ▁of ▁the ▁Har ly ▁Forest . ▁ ▁A ▁section ▁of ▁the ▁A   3 9 5 ▁motor way ▁runs ▁past ▁the ▁Har ly ▁Forest , ▁a ▁few ▁hundred ▁metres ▁east ▁of ▁the ▁old ▁Har lib urg , ▁where ▁it ▁is ▁crossed ▁by ▁the ▁B   2 4 1 ▁federal ▁road . ▁ ▁History ▁ ▁The ▁Har lib urg ▁was ▁built ▁in ▁ 1 2 0 3 ▁by ▁King ▁Otto   IV ▁as ▁an ▁ ▁imperial ▁strong hold . ▁Like ▁the ▁Lie ben burg , ▁that ▁stood ▁around ▁ 1 0   km ▁to ▁the ▁north west , ▁it ▁was ▁intended ▁to ▁threaten ▁the ▁access ▁roads ▁to ▁G os lar , ▁which ▁were ▁held ▁by ▁the ▁H ohen st auf en ▁lord , ▁Philip ▁of ▁Sw ab ia . ▁In ▁ 1 2 1 8 , ▁Otto ▁himself ▁stayed ▁at ▁the ▁castle ▁shortly ▁before ▁his ▁death . ▁ ▁In ▁the ▁late ▁ 1 3 th ▁century , ▁the ▁castle ▁was ▁transferred ▁to ▁the ▁House ▁of ▁W elf . ▁At ▁the ▁Diet ▁of ▁Er furt ▁in ▁ 1 2 9 0 , ▁the ▁Bishop ▁of ▁H ild es heim ▁accused ▁Henry ▁the ▁Ad mi rable ▁of ▁Brun sw ick - Gr uben hagen ▁of ▁breaking ▁the ▁Land fried e ▁or ▁" imper ial ▁peace " ▁that ▁had ▁been ▁in ▁force ▁since ▁ 1 2 8 3 4 , ▁by ▁toler ating ▁highway ▁rob ber y ▁by ▁the ▁soldiers ▁g