Translation:Surely it is not a city?
"Isn't this a city?"
"Surely this is a city?"
I think these two options could potentially indicate an expected negative response.
"Isn't this a city?" suggests an expected positive response, to me. "This isn't a city, is it?" would expect a negative, but that may be too loose a translation for this sentence.
This is such an awkward way to speak in English. Would a loose translation be, "This can't be a city, can it?" or, "Don't tell me they call this a city!"