Nuclear Beasts

Food

Here's one problem. What does the city produce? Where do they get the funds to buy food or where do they grow their won if they're all in a giant city? Let me muse on the possibilities.

• The Halls of Plenty: there are basically magically supported hydroponics facilities scattered throughout the city. The upper class areas have the best ones, ones that grow fancy fresh fruits and spices and even wasteful stuff like flowers. Lower areas grow pathetic tubers and edible greens that can be mashed into paste and the system is often on the verge of failing.
• The Plane of Plenty: there's at least one adjacent world that pays an access/protection fee in the form of food. They might also trade it for reasonable trade goods, like stuff from other worlds that they can't produce themselves (metal implements, perhaps). It could be an "upper" plane where they're all really nice and basically produce more food than they could ever eat, but that seems a bit too idealized for the setting.
• Trade in general: if it's like most big cities, Menagerie will be a net consumer of foodstuffs. Farmers bring food to trade for the local currency, then buy other stuff. Food is cheap, and the farmers remain poor. But without a huge number of thriving farms, this won't really work... the city would starve itself down to a reasonable size (of course, a small, shrunken population occupying a giant stone city might make a better setting, anyway).
• Create Food Magic: there's a trade for mages who can wish foodstuffs out of thin air. They're always busy, but never lack for work. Acquiring enough mana to do it daily would be the big difficulty; they'd need some way to trade mana around, big time.