This can be spiritual and not just over a real city.
I have created a new city for the worldwide ecclesia.
I see if the body can work in enough unity and link with apostolic resource centres so benches in various domains can link together over a city. This becomes a city of refuge where so much legislative work has been done that everything flows on earth and becomes more like heaven. Then the boundaries between heaven and earth reduce, so eventually there will be a new earth.