sargadae about 500 B.C. Utians Boundaries of Satrapies under Darius I Royal Highway Scale 36000000 intes Figure 1.1 Persian Empire circa 500 BC, and the Royal Mail route. Reproduced with permission of the University of Texas [3] the streams is called the Gyndes, and this is the river which Cyrus dispersed by digging for it three hundred and sixty channels. Leaving Armenia and entering the Matienian country, you have four stations; these passed you find yourself in Cissia, where eleven stations and 42 1/2 parasangs bring you to another navigable stream, the Choaspes, on the banks of which the city of Susa is built. Thus the entire number of the stations is raised to one hundred and eleven; and SO many are in fact the resting-places that one finds between Sardis and Susa [4]. Development and operation of the Royal Highway and Royal Mail depended on a number of technological advances. These included better tools for building roads; better methods for horse breeding; training programmes for horse riding couriers and SO on. Technological development for other applications contributed as well. For example, the development of papyrus as a medium for writing contributed to the operational simplicity as paper was lighter to carry than baked clay and less susceptible to breakage. The location of relay stations was likely determined based partly on a number of these technological parameters. For instance, the inter-station distance would have been a factor of the terrain, as well as the fastest speed a horse could typically travel. Of similar importance were business and operational issues including the costs of operation and maintenance of stations, the number of couriers and their rotation, the security of the stations and SO on. These issues and associated costs would have been weighed against the value of telecommunications speed: how important was a 7-day end-to-end travel compared with an 8-day or 6-day travel? In modern days a cost-benefit analysis (CBA) or a cost- effectiveness analysis (CEA) is usually undertaken t