The Pharos was a marble watchtower and lighthouse built in 280 BC on an island in the harbor of Alexandria, Egypt. Estimated to have been 300 feet high, the primary function of the lighthouse was to guide approaching ships to the harbor on an otherwise unmarked coast. Historians debate whether fires were burned on the top of the tower, or whether mirrors were used to reflect sunlight. Since ships rarely sailed along coasts at night, there was probably little need for the lighthouse after dark. The Pharos was destroyed in the 14th century, after having been damaged by several earthquakes.