Forgery or imitation from the era of the royal denarius of Boleslaw II.
Completely different in style, as can be seen especially on the side with the building, or the mark behind the figure of the ruler.
Very rare.
A variety not described in Kopicki or Stronczynski, among others. In Corpus Nummorum Poloniae we find an engraving with an inverted Z, but this is a different variety.
