I considered all three options but I found none of them suitable.
For completeness, here is the picture that was attached to the note: https://westnordost.de/p/147692.jpg
You can see that the steps are solid blocks of sandstone, not sett, not paving stones or cobblestones. In Karlsruhe, there are lots of buildings made of sandstone, and often their stairways are made like in the picture.