[Bruno]

Assuming the rough default of a 1.25mi (2km) on a side space for Caverntown, and not fiddling with the ratio of height to x-y dimensions, how high is the dome ceiling of the cavern?
I'm noodling around with making a model of caverntown in Blender, but PCs will inevitably want to fly or unleash a giant flying monster or both. How much clearance over houses and how high you can get and make guards/PCs get big range penalties to hit you is interesting (And as always, falling damage! PCs will find a way to take falling damage even on the arctic tundra. True story).

Height also indirectly controls how tall the buildings are going to get. If e.g. the ceiling is 30', and people have a roof patio, they're never getting more than 2 floors (including ground floor, not counting on top the roof) "above ground" and you'll not have a lot of space to maneuver over parapets and any roof-top gazebos. It will also cramp the style of the druids trees.

If the ceiling is 600' you can get some classy aerial dogfights going, and PCs make a satisfying splat noise if they fall.

Side note: The stairs to the surface around the shaft seem to be about 60-odd flights [1], so presuming a 10' rise per flight, the ceiling isn't 600 feet. But that's still an awe-inspiring mental picture.

[1] Someone with a move of 7 and a high enough HT or Running that they didn't have to make significant rest stops can run the steps up the shaft in about 7m 9s. The winner of the Empire State Building stair climb did 86 flights of stairs in 10m 16s, let's say he's our Move 7/healthy runner. That suggests the steps are ~60.5 flights of stairs. Unless I have my math wrong, which I could. It might be 390' instead of 600 ft.