I am reading Prelude to Foundation which occurs around the year 20,000. With the exception of the Imperial Palace, all 45 Billion People live under domes. In one scene Hari Seldon is on the top of the domes, which are covered with dust deep enough for trees to grow.
It seems that there may be sufficient resources (not sure) for a malcontent or group, to survive nicely on top of the domes. Is there any indication (canon) of people living on top of the domes of Trantor?
If major spoilers please hide, I am actively reading the foundation series.