Urban Maps

I found these urban maps in the back of an empty planner at work.  Each map represents a different international city.  I'm really intrigued by the structural differences in each map - some are nebulously interwoven and organic, while others are centralized, rigid and concentric.  I wonder what mixes of sociology and environmental ecology lead to the development of these geometric structures... do these concepts lay hidden deep in the networked pathways of our brains, or do they emerge from the ebb and flow of human relations?  Perhaps a little both... nonetheless, I find the complex connections to be very stimulating.