No-one really knows the origins of lighthouses, but we can safely say that families whose members were at sea would hope that the lights in the windows of their homes would help guide their loved ones back safely. It goes without saying that a light placed in a prominent position such as on a roof or on top of a high tower would be much more visible. The better and more easily distinguishable the light, the more successful it would be. Thus, the derivation of the word 'lighthouse' seems obvious, yet the French simply use the word 'phare' which is derived from the ancient light tower at Pharos near Alexandria. Spaniards and Italians use very similar words, whilst Germans refer to a 'Leuchtturme' or light-tower. Lexicographers have argued in vain that, in English, the word 'pharos' should have been adopted, but this has partly been addressed because 'pharology' is the accepted word to mean 'the study of things related to lighthouses'.
An original pharos exists in English territory inside the grounds of Dover Castle, although it has been much altered over the centuries. Probably built in the reign of Emperor Claudius, it formed one of a pair of fire towers, the other being built at Boulogne some forty years earlier in the reign of Caligula. It has been argued that it may have been used as much for signalling across the English Channel as for showing lights, but there is no doubt that it did serve the purpose of a lighthouse for some of its history.