Cool. It's not that I'm being secretive it's just that specifics will have to work themselves out later.
I strongly want cities to be based on indigenous material. The reasons the Romans/Greeks built the way they did was because of the material (marble) available to them. The reason the Egyptians built the way they did was because of sandstone... which is why they tended to have buildings with a ton of columns internally and largely why the pyramids are pyramids.
So, the fact that I haven't figured out how such stone as marble, granite, etc. will be allocated throughout the land and what an NPC-run quarry will even look like, exactly, it's hard to say how far I can take that.
I will say that I've designed several different 'hovel' level houses based on land types and real world examples from the past. From half buried-in-sand sort of small yurts to many of the huts and thatched cottages you've already seen. Using sand instead of sandstone, I've also prototyped some desert city architectures, too. Someone on the Mythruna server even had some cool shaped stone doorways that I will appropriate for desert style large gateways.
In fact, the only architecture that I still haven't found a handful of useful techniques for is medieval city architecture, ironically. I mean, I have the standard "waddle and daub" stuff but that is more of a village thing to me at this point. Sure cities will be filled with it but I still struggle to come up with a stone-and-mortar based house/building that I like. I have some ideas on things I can do with some new block types, though... and maybe I can finally retire the current stone brick material for something more appropriate.
Stone bricks weren't all there was. There's a pub in N'Orleans that's about 300 years old and is still standing. It's made of clay
bricks, but clay bricks are far older than just that. Look up some of the older European buildings. The 17th century wasn't all castles and daub.
... It's just that alot of residential brick buildings fell apart, so we don't talk about that. It's the little secret historians are ashamed to talk about. (Germany, on the other hand...)