Somebody should explore if Stonehenge, Carnac stones, and other megalithic formations were banking and payment systems.

More recently, in the isle of Yap, they used big Rai stones as money.

Many megalithic buildings are tombs, places of worship, or served as calendars, but many big stones aligned in open spaces have no conclusive explanation.

I suggest they could have been a way of storing value and were used for payments too. There is evidence that there was trade across the European continent and into the middle east in those times (~6000 BC). Central marketplaces where they raised the stones and met to trade could have been a use case. The stones obviously stayed there, with a consensus of who owned them, and the next season of trade they would use them as money again.

To move huge stones and align them takes a lot of time and effort, but greed may be a strong incentive to have built those formations.