Iskanderun preserves the name, but probably not the exact site, of Alexandria ad Issum, founded by Alexander the Great in 333 BC, about 23 miles south of the scene of his victory, to supersede Myriandrus as key of the Syrian Gates (Beilan Pass). The importance of the place ever since has been derived from its relation to this pass, the easiest approach to the open ground of Hatay and Northern Syria; and this relation has prevailed over the extreme unhealthiness of the site, which lies on marshy deltaic ground, screened by the horseshoe of Elma Dagh from all purifying influences of north and east winds. As the main outlet for the overland trade from Baghdad and India, whose importance was great until the establishment of the Egyptian overland route, the place was a great resort, first of Genoese and Venetian merchants, then of those of West and North European nations. The British Levant (Turkey) Company maintained an agency and factory here for 200 years, till 1825, in spite of appalling mortality among its employees. Alexandretta is still the main port for the Aleppo region, to which a good chaussee leads over the Beilan Pass, and it has a considerable export trade in tobacco, silk, cereals, liquorice, textiles.
The health of the place has improved with the draining of the marshes and the provision of a better supply of water, but still leaves much to be desired. The wealthier inhabitants have summer residences at Beilan near the summit of the pass, long a stronghold of freebooting Dere Beys and the scene of the victory won by Ibrahim Pasha in 1832, which opened Cilicia to his advance. The distance by road to Aleppo has been shortened to about 70 miles, and Antioch is about 45 miles distant by a branch of the same chaussee.
(from an old encyclopedia)