The Berlin Wall, which surrounded West Berlin, was 96 miles long. Of this perimeter, the border between West Berlin and surrounding East Germany was 69.5 miles, while the border between East and West Berlin was 26.8 miles.
Construction of the Berlin Wall began in 1961. The Communist government of the German Democratic Republic, as East Germany was officially known, placed the wall inside East German territory. Over the decades of the wall's existence, numerous improvements were made to prohibit escape or emigration from East Germany. The most visible portion of the border controls was the wall itself. The fourth and final upgrade was constructed from 1975 to 1980, and consisted of 12 foot high concrete slabs backed by watchtowers, dog patrols, barbed wire and a cleared "death strip" that made shooting trespassers easier.