Lighthouse of Alexandria

The Lighthouse of Alexandria or The Pharos of Alexandria was a tower built in the 3rd century BC (between 285 and 247 BC) on the island of Pharos in Alexandria, Egypt to serve as that port's landmark, and later, its lighthouse.
With a height variously estimated at between 115 and 150 m (380 and 490 ft) it was among the tallest man-made structures on Earth for many centuries, and was identified as one of the Seven Wonders of the Ancient World by Antipater of Sidon. It may have been the third tallest building after the two Great Pyramids (of Khufu and Khafra) for its entire life. Some scholars estimate that would make the tower the tallest building up to the 14th century.
Pharos was a small island just off the coast of Alexandria. It was linked to the mainland by a man-made connection named the Heptastadion, which thus formed one side of the city's harbor. As the Egyptian coast is very flat and lacking in the kind of landmark used at the time for navigation, a marker of some sort at the mouth of the harbour was deemed necessary—a function the Pharos was initially designed to serve. Use of the building as a lighthouse, with a fire and reflective mirrors at the top, is thought to date to around the 1st century AD, during the Roman period. Prior to that time the Pharos served solely as a landmark or day beacon.

[edit] Construction and destruction
The lighthouse was completed in the 3rd century B.C., after having been initiated by Satrap (governor) Ptolemy I Soter, Egypt's first Macedonian ruler and a general of Alexander the Great. After Alexander died unexpectedly at age 32, Ptolemy Soter (Saviour, named so by the inhabitants of Rhodes) made himself king in 305 B.C. and ordered the construction of the Pharos shortly thereafter. The building was finished during the reign of his son, Ptolemy Philadelphos.
According to legend, Sostratus was forbidden by Ptolemy from putting his name on his work. But the architect left the following inscription on the base's walls nonetheless: "Sostratus, the son of Dexiphanes, the Cnidian, dedicated (or erected) this to the Saviour gods, on behalf of those who sail the seas"; the original Greek inscription "ΣΟΣΤΡΑΤΟΣ ΔΕΞΙΦΑΝΟΥ ΚΝΙΔΙΟΣ ΘΕΟΙΣ ΣΩΤΕΡΣΙΝ ΥΠΕΡ ΤΩΝ ΠΛΩΙΖΟΜΕΝΩΝ" literally means: "Sostratos of Dexiphanes [meaning: son of Dexiphanes] the Cnidian to Saviour Gods for the seafarers (or seafaring [ones])". These words were hidden under a layer of plaster, on top of which was chiseled another inscription honoring Ptolemy the king as builder of the Pharos. After centuries the plaster wore away, revealing the name of Sostratus.
The lighthouse was badly damaged in the earthquake of 956, then again in 1303 and 1323.