The coastline along which the towers were built was one of the first areas of Britain to be mapped accurately using triangulation. Because it was believed to be the most likely place for an invasion, it was vital that the British Army had better, more accurate maps for the area than an invading French force. Once the invasion coasts had been mapped, the rest of Britain was mapped, under what was to become the Ordnance Survey.
Early O.S. maps are those on which the Interactive Map (165k) is based: those produced by Colonel Mudge, published in 1813 (Sussex) and 1816 (Kent). The reason for this is to show why the towers were built where they were, something that is not clear in every case when seen on map of a modern coastline. For example, on a modern map, Tower 28 stands almost a mile inland, whereas it was on the coast overlooking the sands of Rye Harbour when first built.
The Interactive Map is a very large image with a file-size of 165k - if you have a slow internet connection, you may not want to download it, so below is a non-functional half-size copy to show you what you're missing.
