The Pillars of Hercules (Columnae Herculis, , Aʿmidat Hiraql, Columnas de Hércules) was the phrase that was applied in antiquity to the promontories that flank the entrance to the Strait of Gibraltar. The northern Pillar, Calpe Mons, is the Rock of Gibraltar. A corresponding North African peak not being predominant, the identity of the southern Pillar, Abila Mons, has been disputed throughout history, with the two most likely candidates being Monte Hacho in Ceuta and Jebel Musa in Morocco.
According to Greek mythology adopted by the Etruscans and Romans, when Hercules had to perform twelve labours, one of them (the tenth) was to fetch the Cattle of Geryon of the far West and bring them to Eurystheus; this marked the westward extent of his travels. A lost passage of Pindar quoted by Strabo was the earliest traceable reference in this context: "the pillars which Pindar calls the 'gates of Gades' when he asserts that they are the farthermost limits reached by Heracles". Since there has been a one-to-one association between Heracles and Melqart since Herodotus, the "Pillars of Melqart" in the temple near Gades/Gádeira (modern Cádiz) have sometimes been considered to be the true Pillars of Hercules.
Plato placed the legendary island of Atlantis beyond the "Pillars of Hercules". Renaissance tradition says the pillars bore the warning Ne plus ultra (also Non plus ultra, "nothing further beyond"), serving as a warning to sailors and navigators to go no further.
According to some Roman sources, while on his way to the garden of the Hesperides on the island of Erytheia, Hercules had to cross the mountain that was once Atlas. Instead of climbing the great mountain, Hercules used his superhuman strength to smash through it. By doing so, he connected the Atlantic Ocean to the Mediterranean Sea and formed the Strait of Gibraltar. One part of the split mountain is Gibraltar and the other is either Monte Hacho or Jebel Musa. These two mountains taken together have since then been known as the Pillars of Hercules, though other natural features have been associated with the name.