Or to be more specific, urbanist Kevin Lynch’s city maps from his 1960 book The Image of the City. I’ve described his approach here (March 2021) (where I also pick at the possible neurological underpinnings) so to briefly summarise:
Lynch puts forward five primitive elements: paths (e.g. streets); edges (e.g. uncrossable rivers); districts; nodes (e.g. street corners); landmarks (e.g. a recognisable building). Each element has an intuitive way to sketch it, as if on the back of a napkin.
