Freinshemius, in his supplement to Livy, relates, after Leo the African[15], that the tomb of Alexander the Great was still to be seen in his time, and that it was reverenced by the Mohammedans, as the monument, not only of an illustrious king, but of a great prophet. [16] The ancient city, together with its suburbs, was about seven leagues in length; and Diodorus informs us that the number of its inhabitants amounted to above 300,000, consisting only of the citizens and freemen; but that, reckoning the slaves and foreigners, they were allowed, at a moderate computation, to be upwards of a million. These vast numbers of people were enticed to settle here by the convenient situation of the place for commerce; since, besides the advantage of a communication to the eastern countries by the canal cut out of the Nile into the Red Sea, it had two very spacious and commodious ports, capable of containing the shipping of all the then trading nations in the world. The harbour, called Portus Eunostus, lay in the centre of the city; thus rendering the ships secure, not only by nature but by art. The figure of this harbour was a circle, the entrance being nearly closed up by two artificial moles, which left a passage for two ships only to pass abreast. At the western extremity of one of these moles stood the celebrated tower called Pharos. The ruins of it are buried in the sea, at the bottom of which, in a calm day, one may easily distinguish large columns and several vast pieces of marble, which give sufficient proofs of the magnificence of the building in which they were anciently employed. This light-house was erected by Ptolemy Philadelphus. Its architect was Sostratus of Cnidos; its cost was 180,000_l._ sterling, and it was reckoned one of the seven wonders of the world[17]. It was a large square structure built of white marble, on the top of which a fire was constantly kept burning, in order to guide ships by night. Pharos was originally an island at the distance nearly of a mile from the continent, but was afterwards joined to it by a causeway like that of Tyre. This Pharos was destroyed, and, in its stead, a square castle was built without taste or ornament, and incapable of sustaining the fire of a single vessel of the line: at present, in a space of two leagues, walled round, nothing is to be seen but marble columns lying in the dust, and sawed in pieces; for the Turks make mill-stones of them; together with the remains of pilasters, capitals, obelisks, and mountains of ruins heaped on each other.