If you happen to be near the Science Museum in London (which is free), I recommend a quick visit to the aviation section. On display there is a section, taken like a slice of cucumber, of a Boeing 747. The section is through the double deck area of the plane, and has seats, lockers wiring and piping in place. If, like me, you only normally get to see a passenger’s view of a plane, then this display gives an idea of the size and complexity of a modern wide body and also how elegantly engineered it is.