725 towering arcologies hold a million people up to a mile into the sky with another nine million living in the underground hive.
One in Ten live above ground. For the rest, life isn't that good. You've got soul-crushing conditions, labyrinthine designs, rampant crime, corruption and cults, and to top it all off, your air, food and water quality varies wildly (and may contain up to 12% processed malcontents, debtors, and retirees). Also, there is no natural light source and you're forced to work by a brutal enforcer. So it's mainly a population of indoctrinated psychopaths, people who have never experienced sunlight (or even starlight), subsisted on a partial diet of its fellow hive dwellers and who's only connection to anything outside is droning propaganda broadcasts that bellow throughout the hives cramped corridors.
Underground Transportation Tunnels connect to other Hive Towers.