I’m always fascinated by early doodles. Here’s Norman Foster’s first sketch for Stansted airport (from Catalogue: Foster and Partners, Prestel, 2005; reviewed in the London Review of Books, 22 June 2006). At first sight it looks trivial. But actually it conveys the radical idea underpinning the design — which was to put services under the terminal, thereby enabling it to have a light, airy roof.