The westernmost branch of the Nile is blocked from exit to the Mediterranean by a narrow limestone ridge running west to east from the Libyan desert. The Nile, diverted eastward along this ridge, forms Lake Mareotis, finally issuing to the sea at Abuqir. Seven miles west of Abuqir lies the small island of Pharos, offering a sheltered harbour from the prevailing northerly winds.
During his lightning Egyptian campaign in 331 BC, Alexander immediately saw the strategic importance of the site. He ordered Dinocrates of Rhodes, architect of the Temple of Diana at Ephesus, to plan a great city. The city, to be called Alexandria was laid out in the form of a parallelogram 1 1/2 to 2 miles wide, and 4 miles long. Eleven great parallel thoroughfares 100 feet (30 metres) wide were laid out in the direction of the prevailing north-west wind. Perpendicular to these ran seven streets 45 feet (14 metres) wide (Fig. 16.1).
Following the death of Alexander in 323 BC, his empire was shared out between his generals. The Commander of Alexander's bodyguard, Ptolemy Lagus, chose the Governorship of Egypt. By the end of 323 BC Ptolemy was in Alexandria. In Alexander's absence his Superintendent of Finances, Cleomenes, had made himself dictator. Ptolemy's first acts were to depose Cleomenes and execute him. After fighting off an attack by Perdiccas, another of Alexander's generals, Ptolemy was master of Egypt. Alexander's body, brought from Babylon, was buried in a magnificent tomb, the Soma, at the centre of Alexandria. Under Ptolemy I Alexandria grew into the greatest city of the Mediterranean world. At the age of eighty in 284 BC, Ptolemy I, nicknamed 'Soter' (Saviour), since his fleet once saved the Rhodians from starvation during a siege, abdicated in favour of his son Philadelphus.
In about 270 BC, Ptolemy II Philadelphus commissioned Sostratos of Cnidus to build a great lighthouse on the island of Pharos. This lighthouse, called the Pharos of Alexandria, was one of the Seven Wonders of the Ancient World. It stood 440 feet (134 metres) high, having a square base, octagonal midsection, and circular top. In the topmost section stood a