Ever since John Kampfner was a young journalist in Communist east Berlin, he hasn't been able to get the city out of his mind. It is a place tortured by its past, obsessed with memories, a place where traumas are unleashed and the traumatised have gathered. Hit by plague, fire and war, it is a city of reinvention, a city that is always becoming. Over the past four years Kampfner has walked the length and breadth of Berlin, delving into the archives,...