The word «lighthouse» comes from the tower that had been set up in Alexandria, Egypt, on the islet called Faros outside the city’s port. The coast in the area of the Nile’s Delta is very low and does not have obvious signs so that the navigators, who come from the open sea, know which point of the coast they are approaching. At the top of the tall tower brushwood burned during the day, leaving dense smoke and strong fire at night. Thus, ships could see from afar the position of Alexandria, and could be oriented with security towards the entrance of the port. Therefore, the Tower of Alexandria gave its name to every similar construction up until today. A lighthouse is a tower or other type of building that has been designed in order to emit light from a system of lamps and lenses, and is used as a navigational aid for the navigators at sea or inland waterways. Lighthouses mark dangerous coasts, dangerous shallows, reefs, rocks, and safe harbor entrances. In former times they were used widely in navigation; today, however, they have been replaced as the main navigational aid by GPS, and other more sophisticated and accurate electronic navigation systems. In geographical areas such as the Aegean and the Ionian seas, lighthouses even today retain their value intact as navigational aids since the small boats and caiques, despite the development of GPS, rely to a large extent on the visual observation of the environment they move in.