What is the future of the city? Major cities are the most efficient. Their improvement along zero carbon lines would include harvesting every last bit of sunlight. Solar thermal generators at each floor level heat the city in the spring and fall. Green walls would cool them along with solar electric. The city would be like a three story woodland or rain forest depending on your environment.
We mention Palo Soleri because of a visit to Arcosanti, an example of a beehive type of city neighborhood skyscraper. And Boeing would be a good example of large flying objects.