Like straight out of a novel or ttrpg scenario:
In ancient Turku, there is a prison asylum on a hill. Kakola.
The word means "place for the insane".
The hill has been named after the asylum, and so has the grade of granite found in it.
The stone, Kakolite, has been used for many buildings in the area, including the prison, the ancient cathedral, the art museum, etc.

Like, we all know how this ends, right?

#storyseeds #eldritchStone