That's true. If they didn't accept it, that's probably because they wanted to stress the fact that byen is in the definite, so they want us to put "the town" or "the city".
Denne / dette / disse - this (fk) / this (n) / these
Den / det / de - that (fk) / that (n) / those
If you have a clause saying "it/this/that is", you use the neuter form, no matter the actual gender of the noun it refers to.
That would make it plural, resulting in "these are my parts of the city" - "Disse er mine dele af byen." So, no.