"How big is the city hall's bathroom?" <-- is possessive wrong there? I was not aware of the usage of it in English.
The possessive is not often used with inanimate objects.
Washroom not accepted 2018-04-05
Washroom still not accepted 2020-10-06. Please be kind to regional dialects. We almost never say "bathroom" where I'm from :'(
That's a really useful one, thanks Duo
Asking the important questions
Shouldn't there be an "의" or "에" after city hall? Either "the bathroom belonging to City Hall" or "the bathroom at City Hall"?
These might be omitted when they're obvious. That what me Korean teacher told me once.
Please note that "에" is not correct here. In case you'd like to use it the sentence requires some changes.
What about "restroom" for 화장실?
Is that totally wrong?
I used "restroom" in my answer and it was accepted.
Next time when I re-do the Korean course I'll try it