Pillars of Heracles

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.
However in world the two Enormous Mountains found either side of the Eastern entrance to the Vóreios Sea. Famously they are said to be a result of the hero Heracles tearing apart the earth to let the water flow, connecting the two bodies of water, the Vóreios Sea and the Imisélinos Sea. The remains of the earth he pulled aside, settled into the two large mountains we know today.
Recently they have come to the parties attention when they followed the Owl and Spear's avian spy to the area of the pillars on the other side of the Vóreios Sea, the spy being followed promptly disappeared, and the party are now unsure of it's purpose.