A landscape or city is legible when it conveys information about itself. A place is most legible when it conveys information without the obvious devices of communication. Legibility is a kind of follow-your-nose sense that allows you to understand a place from both macro and micro signals.
Manhattan is legible though a grid punctuated by landmarks.
Miami Beach is ever-oriented between ocean and bay.
Most Greek villages run from a port, up the hill to a fort or church that takes the high ground.
The ebb and flow of commercial activity and social life in these places can be anticipated. You can figure out where the main shopping streets are and where people go to relax.
Legibility works in different dimensions–from an aerial view popes, princes, and architects identify axes and connections through a city. But for the average boulevardier, legibility works in three dimensions, the feeling of the city as you walk through it, not fly over it in your royal helicopter.
Sure Parisian boulevards are magnificent,
but this is why we go to Paris.
Just because things look neat on a plan, doesn’t mean they will be neat to experience in real life.