We’re hearing lots about walls these days� With some luck, and often a great deal of hardship, walls can come down. The Berlin Wall, of course, fell 20 years ago today. That’s a crowd cheering after the toppling of a mock wall today in Berlin. Artists often play a part in the struggle against barriers. The World’s Gerry Hadden has been looking into what songs symbolized the struggle against the divided Germany. He didn’t find many. But the few he did find mostly came from the former East Germany where artists didn’t have the freedom to say what they meant.