The former "inner German border", making Germany into an 'East' and a 'West', also divided the Harz region in two separate parts. At the actual spot of this border is now a memorial stone that commorates the reunification of Germany with the words "Deutschland wieder vereint" ('Germany united again').
Along the road near the city of Braunlage is a sign that says that: Here, Germany and Europe were separated until 2:30 pm on November 12, 1989".
And on both sides of the road the former patrol road is still visible -even though trees have grown into it by now-: two parallel lines of perforated concrete blocks that ran beside the border. Guards used this all-weather road to 'travel rapidly to the scene of an attempted crossing' (info from Wikipedia).