Communications and telecommunications are always important to a city. The first type of communications was with runners (on foot or on horse). The need of something faster made them decide to use signals with fire. After a while they had the first code for using fire signals. On hills or mountains near the city there were special personnel for such communications.
Here is a sample of how the code was working: the alphabet was divided in 5 rows and 5 columns. So they used 2 groups of 5 fires to indicate which letter they wanted to transfer. They could transfer this way up to 20 or 25 words every hour. It was not very fast but it was working! The low speed forced them to use stenography with prearranged code. So the famous from the Usenet 'CUL8R' (see you later) is not such a new invention! :-) When Troy fell into the hands of the Greeks, the rest of Greece knew it in a day's time by using this system!
This type of communication with fire signals was also used in a simpler form. The time period was divided in hours and for each hour there was a predefined message. So if the fire was on at 12 o' clock it could mean 'send army' or whatever... This system was simpler but it was easier to use without specially trained personnel and could cover longer distances with the least of fires!
Another type of visual signals used moving flags. I think such a system is still used by the Navy.
The fire signals are probably helped by reflectors in order to get even further. According to History, the famous Lighthouse of Alexandria used such a reflector or even a lens to guide its light as far as possible.
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