Having on several occasions whiled away an afternoon in the Museum of London, I knew that it could only be accessed from a high-level walkway above London Wall but I’d never given this too much thought. I also knew of a couple of pedestrian bridges I’d spotted that I had no idea where they went. And of course I knew about the weird concrete maze of the Barbican — London’s ugliest building by far — but I didn’t know they were related, part of a deliberate post-war plan to build the city of the future. They called it the Pedway!