I found some old photos from an Arete West high school track trip organized by my father in 1981. They depict our walk to Check Point Charlie to enter East Berlin.

The 1981 Arete West track team posing along the western side of the Berlin wall.
Crossing "no-mans-land" between the western and eastern posts of Check Point Charlie as we prepare to enter east Berlin on foot.
The "wall" of Berlin was often a "zone" well built to keep people in. This photo was taken from a raised platform on the western side looking across and along the wall.