I was once bored during the lunch break of a conference being held at the Institute of Civil Engineers, so I wandered into their bookshop. There was a wonderful tome just on the civil engineering of the M25 - yard by yard descriptions. I learnt that my local stretch from J9 towards the new Cobham services is in fact a low-height concrete viaduct over a flood plain that the author opined was the most impressive structure of the whole M25. And there was me thinking it was just a road.
