According to an old and well-known legend throughout Germany, the Kalisz grinding stone (Schleifstein) was used to polish the tongue of liars and bullies. This severe punishment converted them to the path of truth and taught politeness. After 1945, the grinding stone was lost.
In 2003 he came across him during forestry work. It has been restored and returned to its former place in the forest on the Młyńskie Lake, along the Forest Education Path route. A replica of the grinding stone is also located next to the City Hall building.