Don`t Brits do such things to their gone historic places?
Well yes we do, but as I said before, I could find no mention of those tablet type things reading about the city walls etc in English searches, they were mentioned only when I searched in Polish. Still it was a very good riddle, and I've learned lots about the Planty and City Walls :)
There is one more riddle in post 57.
The bit where you say " Where are such conditions?", as I answered the other questions in posts 58 and 60.
The poster is advertising the fantasy opera Opowieści Hoffmanna by Jacques Offenbach. Someone doesn't like opera? I notice there is a rip in the picture, someone's torn the heart out of it? ;) Or is it something to do with the story of the opera itself?