[chrispenycate]

When I said "City-sized" I wasn't thinking of actual city; it's just that there's nothing much between the scale of a mountain and a small country. Besides, they're going to be in majority from equatorial regions, because of the pirouette effect (Quito, perhaps?)
But if you want your cities setting off, you need your spindizzies (you have read Blish's "A life for the stars", Earthman come home" and "A clash of symbols" I trust?)

But the problem with all this is the timing; without doing experiments (and people are so unreasonably upset about me doing experiments) it's so difficult to estimate how long any section of this will take.