Overcast day today and not in the good way (aka the way that provides for great pictures). So instead you get a few lousy ones taken by artificial light:
Collected all the pictures I could find, and watched Let's Play videos on YouTube as well to get a sense of the structure. Eyeballed the scale in terms of how big the Dragon Age avatars looked next to it and drew out some rough sketches scaled in Smoots. Borrowed a lead miniature and measured that and came up with a compromise scaling factor of Smoot-to-centimeter.
This was actually my second attempt, refining from the first. There are still compromises (mostly imposed from wanting to be in equal mm or cm for simplicity in transferring measurements, but also due to the fact that the in-game model is, well, a bit of a cludge.) This functions both as a scaleable reference, and as a sanity-check; sometimes you just don't know what the thing really looks like until you mock it up. My feeling is, this is slightly large in some dimensions, but it seems to work.
No point in taking drawings or mock-ups further; the rest of the work takes place on the actual masters:
I was afraid balsa would be too soft and come apart or at least get dented when I was trying to work it. So despite it being tougher to work, I'm attempting this in basswood. The grain is creating some issues, but it seems to seal okay with just paint -- I was prepared to have to seal with superglue in order to get a decent surface.
Also from experiments, Krylon spray-stone gives some (but not all) of the necessary texture. Fortunately I've already learned how to dab and scumble Bondo Spot Putty to get a more interesting surface texture.
Still, all these cut-out arch segments and stone joints are a pain, and if I had the concentration I'd work up a way to laser-cut a bunch of it.