GRIDS

The groma was an extremely simple instrument, possibly of Greek origin, which became almost the trademark of the Roman land surveyor. Because its function was limited to sighting and setting out straight lines and right angles, its use was restricted to surveying roads and the like and to establishing the rectangular grids of towns, military forts and, above all, land divisions. Since roads form the subject of Chapter II, we may here confine ourselves to a brief outline of the history of surveyed grids.

An irregular street pattern was normal to early Greek cities; but in later times a regular rectangular grid became more widespread. Its introduction was generally attributed to Hippodamus of Miletus who rebuilt a number of cities in this way in the first half of the fifth century BC, and certainly it was a commonplace by 414 BC when Aristophanes lampooned the astronomer Meton as a town planner laying out Cloudcuckooland. But while Hippodamus may have popularised the grid, he did not introduce it, for there are many Greek instances from earlier centuries, and even Egyptian and Mesopotamian antecedents. It was most commonly applied to Greek colonies overseas, which often had the advantage of being built on virgin sites.