Music soundtracks our travels, kills time and distracts, entertainingly. In Berlin, which has more than 300 train stations and where you can see everything panoramically from the overhead S-Bahn, a well-loaded smartphone or MP3 player turns a journey into a film with a score. I have more records related to Berlin than to any other city. I can’t help feeling the city should have a nexus or mother venue where all the currents cross – a musical equivalent of the mighty Berlin Hauptbahnhof, opened in 2006, a powerful symbol of reunification. But which artists would play there? For a child...