The phrase related to the Pillars of Hercules dates back to Antiquity. It was used to describe the promontories (the capes, actually) that surrounded the entrance of the Strait of Gibraltar. These pillars are two in number and they are situated to the North and South. The British Rock of Gibraltar is the northern one and belongs to the UK overseas territories on the border between the Atlantic Ocean and the Mediterranean Sea. While there are two competitors for the southern pillar – Monte Hacho (Ceuta, Spain) and Jebel Musa (part of the Rif Mountains, Morocco).
The proximity of Gibraltar to 15th century Spanish kingdoms, was the reason why King Fernando II of Aragon adopted these pillars in the Spanish coat of arms in 1492.
He also added a banner saying “Non plus ultra” which meant “Spain is everything and there is nothing farther beyond the Pillars of Hercules”. Soon after Christopher Columbus discovered the New World in the same year, the King ordered this “non” to be deleted from the coat of arms and thus the sign changed to “Plus ultra” meaning “Spain is everything and it stretches farther beyond the Pillars of Hercules”. Since then the two pillars and the Plus ultra slogan have been the Spanish national emblem on the national flag and the country’s motto, respectively.
During the Age of Discovery Spain was the most active explorer and conqueror of the new lands, especially to the South. Spanish colonial real, known as the Spanish dollar (“peso de a ocho” or “piece of eight” in English), was the only currency unit exchanged in the New World till 1850. Of course, the Spanish coat of arms representing the country’s possessions beyond the Ocean was an inevitable part of the minted silver and golden coins and it was stamped on them every time. What was depicted on those coins exactly? The two Pillars of Hercules stretched over two hemispheres and a ribbon in the form of the letter “S” rolled up around each of them. These coins were widely spread out on three continents – America, Europe and Asia and because the Spanish trade coinage was internationally recognized at that time, traders started using the two-pillar-ribbon sign only. They didn’t write down the whole word for dollars or peso but they just put that symbol after the respective sums. Later this symbol evolved and it turned into the well known dollar sign – a simple “S” (the ribbon inverted) with two bars (the two Pillars of Hercules) vertically placed.
Being on this topic, maybe it would be interesting to mention a few words about the origin of the word dollar. According to one theory, the word is either of Flemish or Low German origin. The root of the word is daler (or t(h)aler in German) and it’s the short for Joachimstaler. And probably you will ask what Joachimstaler is. It is a coin …. a coin minted in Joachimstal (today’s Jáchymov) in Bohemia, the Czech Republic. That name was applied to a currency coin exchanged in both American colonial territories and it was adopted as the name of the US currency later, in the 18th century.