Our ears popped a few times while seagull music and images played from a dozen little plasma screens scattered around its walls. Then the doors opened and we walked out onto the observation deck. The view seemed very familiar. That confused me. Here I was, up on the tallest building in the world and I felt like I’d seen this sort of thing before. I was looking down past the tops of skyscrapers at snaking road and rail systems. Then I realised that I had indeed seen cities from this viewpoint many times before. From a plane.