I know there's a word to describe the use of the words "City Hall" in the common phrase "you can't fight City Hall", where "City Hall" = "the office of the mayor of the city", but I can't remember what it is. I don't think it's anthropomorphism but the proper term has been on the tip of my tongue all day and I just can't bring it to mind.
Yours is a textbook case of metonymy, which Silva Rhetorica by BYU's Gideon Burton defines as
Reference to something or someone by naming one of its attributes.
City hall is a building associated with local government, and used metaphorically to represent local government as a whole. See also What is the difference between metonymy and synecdoche?
It is not anthropomorphism because we are not talking about the physical building itself. An anthropomorphism might be represented by something like
Erie's City Hall squats lazily, reaching toward State Street but never quite making it.
The word you are looking for is metonymy.