I think you just need a city. As to modifications if you become ruler, you can change add-ons, for example your realm could be 'Sirion', but you could give it the longer title of 'The municipality of Sirion' or 'Sirion last home of the elves'
You can change government an title systems etc. but I think the name is set, though someone with more knowledge will as like as not disagree!
