Lighthouse

An aid for navigation and pilotage at sea, a lighthouse is a tower building or framework sending out light from a system of lamps and lenses or, in older times, from a fire. Lighthouses are used to mark dangerous coastlines, hazardous shoals away from the coast, safe entries to harbors and can also assist in aerial navigation. Because of modern electronic navigational aids, the number of operational lighthouses has declined to less than 1,500 worldwide.

Perhaps the most famous lighthouse in history is the Lighthouse of Alexandria, built on the island of Pharos in ancient Egypt. The name of the island is still used as the noun for "lighthouse" in some languages, for example:Albanian (far), French (phare), Italian and Spanish (faro), Portuguese (farol), Romanian (far), Swedish (fyr), Bulgarian and Russian (фар), and Greek (φάρος). The word "pharology" (study of the lighthouses) is also derived from the island's name.