The Berlin Marathon, once a pleasant but unremarkable jaunt through the Grunewald forest, was redirected through the streets of West Berlin in 1981. In doing so, it became part of the city for a day. After the Berlin Wall came down in 1989, the race was rerouted again so that it passed through the old East and West Berlin. In that first true city-wide race, on 30 September 1990, three days before Germany was officially reunified, many runners wept as they passed underneath the Brandenburg Gate.
“Two Hours: The Quest to Run the Impossible Marathon” by Ed Caesar, April 09, 2017 at 07:52 PM
Photo from this article (in German) on 25th anniversary of that race.