The ones most numerous in his initial random sample seem pretty good for it although he'll have to watch out for occasional spots of weaker stone.

He enters all the kinds of rock into his rock analysis program so they can be identified going forward and starts panning around the developing model of the cave to find a good spot for a whole-ass city, convenient to the cave-mouth transit system that will have no choice but to be located there.

It will have to be a moderately winding and sprawly whole-ass city unless he wants to go check out a different cave, but there are lots of forks and the passages between them mostly aren't very narrow at all and could fit shorter buildings of their own.  Two of the branches seem to end up partially on top of each other, and after some math it looks like it would be safe to either put in two separate levels of city or to clear out the middle.  This one part is pretty deep and could fit some sunken towers and/or cliffside construction - on further inspection its path eventually leads back out to the side of the cylinder again.  There are like four lakes and a few smaller bodies of water.

It can be a moderately winding and sprawly whole-ass city though he does also investigate, in small models with tension measurements on them, the feasibility of adding additional tunnels between subcaves.

There's a few that are kind of iffy but most of what he tries would be fine.

Marvelous. He will put down some tentative chalk marks as he flies about the cave.

"You know, if you put in space for a zoo, once there were people to staff it and animals to fill it there would be at least one in each time zone.  For the convenience of sleepless and distributedly-sleeping beings."

"I guess a bustling metropolis should have a zoo! And I guess your version of sleep is going to get more common even if mine won't."

"It'll be really interesting to see how other clouds decide to split occupation, vocation, maintenance, and rest between their bodies.  At some later point we should probably also discuss how I'll end up doing that, though I'm fine being on call fourct onect at least until we settle into some sort of stable pattern."

"Don't the bodies all need maintenance and rest at a normal rate?"

"Yes, but I can imagine wanting some time completely off, or other clouds wanting to have all of themselves sleeping at once, that sort of thing."

"I suppose that makes sense! - is 'fourct onect' like 'twenty-four-seven'?"

"As in the number of hours in a day and days in a week?  Yes."

"I will get the hang of it eventually." City city city! He makes a larger screen so Felicity can see as he puts mockups in locations.

"I don't particularly expect them to be depicting anything architecturally sound, but there are a fair number of speculative paintings of these kinds of cities, if you'd like to take some inspiration from the local vision of futuristic."

"Ooh, good to know." Can he find a coffee table book of it or something.

Felicity can name a few artists and from there collections aren't hard to find.  They're really big on things being silver or white or encased in brightly-colored semi-transparent plastic these days, though there are also several other distinct trends.

"I don't know whether you were planning to do different aesthetics for different districts or keep it consistent or what, but if it's a mix I vote this should be one of them."

"I was thinking maybe I'd run a concept art contest for specific neighborhoods or something. The plastic trend, I predict, will not last."

"Say it isn't so!  But I like that idea.  Do you have anything in mind for a place to put stars whose need for resurrection is time-sensitive?"

"I can do something blocky with a modular facade, put up something plagiarized from my world for now and change it later by popular demand."

"Excellent."

"Modular facades are popular in Hell because that way you can have disposable architecture without having to demolish a whole building every time you want a new look."

"How clever!  And there aren't substantial effects on the overall durability?"

"Nothing you can't compensate for with demonic materials science!"

"Then one of those big enough to house a few hundred people seems like a fantastic idea."