Lighthouse of Alexandria

The Lighthouse of Alexandria guided shipping into one of the busiest ports of the ancient world, standing in the delta of the River Nile in Egypt. Known as the Pharos it took its name from the island on which it was built. A Wonder of the Ancient World, the Lighthouse was between 103m and 118m high and stood out on a generally low and featureless coastline. Built in the late 4th century B.C., the lighthouse was damaged by earthquakes and in the late 15th century A.D. a fort was built on the site.

History
In 332 B.C. Alexander the Great conquered Egypt. On the Egyptian coast, near the island of Pharos, was a small fishing village called Rhacotis. He believed the location had potential as a port, and so founded a city there bearing his name: Alexandria. Considered one of the Seven Wonders of the Ancient World, the design of the lighthouse was widely copied and the name pharos became the general term for a lighthouse.

The Greek geographer Strabo writing in the late 1st century B.C. and early 1st century A.D. gave an insight into what made Alexandria suitable as a harbour: “Pharos is an oblong island, is very close to the mainland, and forms with it a harbour with two mouths; for the shore of the mainland forms a bay, since it thrusts two promontories into the open sea, and between there is situated the island, which closes the bay, for it lies lengthwise parallel to the shore … the extremity of the isle is a rock, which is washed all round by the sea and has upon it a tower that is admirably constructed of white marble with many storeys and bears the same name as the island”.

The Lighthouse of Alexandria was built at the eastern end of the island of Pharos. It is not certain when the Lighthouse was built, for instance source written centuries after the event claim it was built in 297 B.C., while another states it was 283/2 B.C. It was was most likely commissioned during the reign of Pharaoh Ptolemy I Sotor (305–282 B.C.) who succeeded Alexander the Great. According to Pliny the Elder writing in the 1st century A.D. the light house cost 800 talents to build. This was a tremendous amount to spend, and was a tenth of the contents of the Pharaoh's treasury in 305. B.C. Pliny the Elder, Lucian, and Strabo all attribute the design of the Lighthouse to a man named Sostratus of Cnidus. It has been suggested that Sostratus commissioned the lighthouse rather than designed it, however the formidable cost of the building programme means it is unlikely that anyone other than the Pharaoh could have financed the work. While Pliny asserts that Ptolemy allowed Sostratus to write his name on the monument, Lucian claims that he hid his name underneath the plaster bearing Ptolemy's name. Over time the plaster would decay leaving Sostratus' own inscription.

Earthquakes in 956, 1303, and 1323 severely damaged the Lighthouse, and in 1477–1479 the Fort Qait Bey was built on the site. Alexandria's coastline has changed significantly since Antiquity, and part of the island of Pharos has become submerged (along with parts of the city itself).

Form and operation
The island was an outcrop of limestone, and the lighthouse itself was built from a type of hardened limestone similar to marble. Arab writers provide heights for the lighthouse, with their figures ranging from 103m to 118m. They also note that the white stones used to build the structure were held together with lead. As a widely recognised building, the Lighthouse of Alexandria was commonly represented on coins, and the depictions are consistent with written evidence for its structure. It consisted of three tiers, the lowest of which was a 30m square base. On top of that was a narrower octagonal structure, which was in turn surmounted by a final stage with a circular plan. Some representations show a statue on top of the Lighthouse, and the figure depicted has been the subject of speculation and whether it was present in the structure's initial design.

While the fire at the top of the Lighthouse was visible from miles away at night, during the day the smoke took over as a beacon. A prodigious amount of fuel would have been required to keep the fire burning, and as Egypt did not have a readily abundant supply of timber animal dung may have been used instead, although naphtha has also been suggested as an alternative. According to the 1st-century historian Josephus, the lighthouse would have been visible from a distance of about 50km.