So I've gone through three different forts now, all reasonable successes, food production is good, defenses all good, withstood titans, forgotten beasts, fires, drought, famine, goblins, trolls, etc.
Now I get it in my head to build a tower. Or even a monolith. Or anything above Z0/Embark level that dwarves will actually walk on.
Build wall. build ramps. Nope. Ok, build wall, build stairs. Nope. Ok, build wall, build bridge. Nope.
So I go to the wiki, and I search the forums, and I read and I read. Everyone is talking about building structures with an interior, like pyramids and so on, but really, I'm not that ambitious. All I want is a wall that dwarves will walk on and/or build on.
My failures so far:
At Z0:
WW
WW
Ok, 2 x 2 square wall, nothing exciting, right, let's build some up stairs around that first 2x2 wall, as scaffolding.
<<
<WW<
<WW<
<<
and... that's as far as it goes. Any attempt to build either on top of the walls or on top of the stairs up is met with two possible results. The first is that the dwarves won't go near it and the second is "No access to building material non-economic item" which I believe basically means "no path to build". This occurs when attempting to build a floor or wall on top of the existing wall, which are my only options from the b-C menu.
The results are similar with ramps compared with stairs. The second level (Z+1) you can paint/designate the down ramps or stairs down on top of the up ramps/stairs up, but the dwarves never build them.
Obviously I'm missing something extremely basic here, but I have no idea what it is. The tower (and indeed, all above ground construction) is now at a halt while I consult with Urist McEngineer to try and figure out this problem.