Strabo Geography 3.5.5

[5] Concerning the foundation of Gades, the Gaditanians report that a certain oracle commanded the Tyrians to found a colony by the Pillars of Hercules. Those who were sent out for the purpose of exploring, when they had arrived at the strait by Calpe, imagined that the capes which form the strait were the boundaries of the habitable earth, as well as of the expedition of Hercules, and consequently they were what the oracle termed the Pillars. They landed on the inside of the straits, at a place where the city of the Exitani now stands. Here they offered sacrifices, which however not being favourable, they returned. After a time others were sent, who advanced about 1500 ¹ stadia beyond the strait, to an island consecrated to Hercules, and lying opposite to Onoba, a city of Iberia: considering that here were the Pillars, they sacrificed to the god, but the sacrifices being again unfavourable, they returned home. In the third voyage they reached Gades, and founded the temple in the eastern part of the island, and the city in the west. On this account some consider that the capes in the strait are the Pillars, others suppose Gades, while others again believe that they lie still farther, beyond Gades. There are also some who think that the Pillars are Calpe, ² and the mountain of Libya which is opposite, named Abilyx, ³ and situated, according to Eratosthenes, amongst the Metagonians, a wandering race. Others fancy that they are two small islands near to the former, one of which is named the Island of Juno. Artemidorus speaks both of the Island of Juno and the temple there, but makes no mention either of mount Abilyx, or the nation of the Metagonians. ⁴ Some have transported hither the Planctae and the Symplgades, supposing them to be the Pillars, which Pindar calls the Gates of Gades, when he says that they were the farthest limits at which Hercules arrived. ⁵ Dicaearchus, Eratosthenes, and Polybius, with most of the Grecians, represent the Pillars as being close to the strait, while the Iberians and Libyans place them at Gades, alleging that there is nothing at all resembling pillars close by the strait. Others pretend that they are the pillars of brass eight cubits high in the temple of Hercules at Gades, on which is inscribed the cost of erecting that edifice; and that the sailors coming there on the completion of their voyage and sacrificing to Hercules, rendered the place so famous that it came to be regarded as the termination of the land and sea. Posidonius thinks this view the most probable of all, and looks upon the oracle and the several expeditions as a Phoenician invention. ⁶ As for the expeditions, what matters it whether any one should vehemently deny or credit the account, as neither the one nor the other would be inconsistent with reason: but the assertion that neither the little islands, nor yet the mountains, bear much resemblance to pillars, and that we should seek for pillars, strictly so called, [set up] either as the termination of the habitable earth, or of the expedition of Hercules, has at all events some reason in it; it being an ancient usage to set up such boundary marks. As for instance the small column which the inhabitants of Rhegium ⁷ erected by the Strait of Sicily, which is indeed a little tower; and the tower called after Pelorus, which is situated opposite to this small column; also the structures called altars ⁸ of the Philaeni, about midway in the land between the Syrtes; likewise it is recorded, that a certain pillar was formerly erected on the Isthmus of Corinth, which the Ionians who took possession of Attica and Megaris when they were driven out of the Peloponnesus, and those who settled in the Peloponnesus, set up in common, and inscribed on the side next Megaris, and on the opposite, Alexander too erected altars as boundaries of his Indian campaign in those parts of the Indies he arrived at, which were situated farthest towards the east, in imitation of Hercules and Bacchus. ⁹ That this custom existed, then, cannot be doubted.