a) If you look at how a US city is laid out on a map, you usually find a grid pattern of streets going from north to south and east to west, and they cross at a very precise 90 degree angle.
d) In cities elsewhere, such as those in many European countries, streets follow a meandering pattern, following the rivers and natural landmarks.
b) This is not simply a case of an older, irregular pattern giving way to a later American invention, however.
c) The ancient Romans, for example, laid out their streets mathematically many years previously, and this also produced a grid pattern.
