I was playing an immortal game where I was employing specialist spam in at least one of my core cities, fueled by cargo ships to feed all the specialists. I started to notice that less and less of the tiles where being worked, until I finally reached the point that the only tiles being worked were a couple GP tile improvements. At that point, I started to realize that I could have begun growing a second city "under" the first, i.e. 4 tiles away to work all the improved land tiles that were no longer being worked by the original city. The second city could have sent another cargo ship to the first city. Ultimately I think there was enough land available elsewhere and/or I did not want the additional city, but still, I thought the concept was interesting. Has anyone employed "nested" cities in BNW by means of internal trade routes?