A decade later, when, in 1987, Bowie returned for the Concert for Berlin, a three-day open-air show in front of the Reichstag, he chose “Heroes” for his performance. By then the city’s Soviet-dominated East had become safer, but it had not become more free. Rock music was treated as a destabilizing threat.

But the wall couldn’t keep out radio waves; the West German–operated, US-run radio station Radio in the American Sector was popular in the East, and had secured rare permission from the performing acts to broadcast the show in its entirety. (Record labels typically opposed this in the 1980s, knowing listeners would record the broadcasts, undercutting album sales.) The concert was held near enough to the border that many East Berliners crowded along the wall to listen to the forbidden American and British music wafting across the city, allowing these two halves of the city to hear the same show, divided but together.
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When Bowie performed on the second night, he began by telling the crowd, in German, “We send our wishes to all our friends who are on the other side of the wall.” He sang “Heroes,” the song he’d recorded in Berlin a decade earlier amid the city’s Cold War fear and violence.

Max Fisher, https://www.vox.com/2016/1/11/10749546/david-bowie-berlin-wall-heroes