My point was that a city is not merely a series of structures and services in a particular geographic region (with its associated climate).
How to put this another way... How malleable should an ideal city be to the lifestyles of its citizens? The fact is that there is feedback between the structure of a city and the lifestyle of its citizens. But the structure is still somewhat inelastic, so you also have selection effects where people who like or dislike a city will move. But this is still limited to the range of choices available (subject to citizenship, employment, family etc). What system would be used to shape the city over time based on the preferences of the citizens? (answers to this question would need to be more specific than say, constitutional democracy)
But there are other questions too: Would an ideal city have citizens with radically different lifestyles to known modern or primitive models?