In a forgotten cavern, if you descend deep enough, you will find the coin columns. There are many hundreds of such columns. Every column consists of 5 to 113 disks that resemble coins. They are made of a very shiny material, resembling gold visually and marble physically. Coins are stacked on top of each other, but not perfectly, so the columns form spiral-like structures. Sometimes they intersect.
We don't know how old they are, who and why made them. It is suspected that the Questioner of the Questioning wall might know something about this location, but he refused to discuss it with the few interlocutors who tried to ask about it.
All the information about these columns come from the Bertswani scrolls.