Is it true that U.S. dollar was created on the Spanish coins "real de a ocho", wich were widely used in the former British Colonies?
They say that the US dollar symbol $ comes from the "Pillars of Hercules", wich were on the Spanish silver coins.
The Spanish Real had the symbol IsI , it is two columns representing the mountains wich separate Europe and Africa and a strip with the inscription in latin language "Plus ultra" (further beyond).

I could not find a better source on the web than Wikipedia (not very reliable in my opinion).
Spanish dollar
Pillars of Hercules