Origins and Ancient Beacons
The earliest navigational lights were open fires kept burning on headlands, tended by communities whose livelihoods depended on returning boats. Written descriptions of deliberate, permanent beacons begin with the Mediterranean, where dense coastal traffic and treacherous approaches made an unmarked harbour mouth a standing hazard.
The most celebrated of these was the Pharos of Alexandria, raised on the island of Pharos off the Egyptian coast during the third century BCE under the Ptolemies. Ancient accounts describe a tiered stone tower of extraordinary height topped by a fire and a mirror arrangement said to project the light far out to sea. The structure survived for well over a millennium before a sequence of earthquakes brought it down, and its name passed into several European languages as the ordinary word for a lighthouse.
Roman engineers built beacon towers across the empire's coastlines, including the tower at Brigantium in what is now A Coruña, Spain. Rebuilt in the sixteenth century, it remains in service and is generally regarded as the oldest lighthouse still operating.
These early beacons shared a common limitation: an open flame is dim, consumes fuel at a punishing rate, and is at the mercy of weather. The light they produced was less a precise navigational instrument than a rough assurance that land, and a harbour, lay in a particular direction.