Strap yourselves in, this is quite the odyssey…!
I decided to get the walls in first, which was as easy as creating one large, flat Plane, then duplicating a few times - Rotations and Translations input manually in the Operator Panel for absolute accuracy.
Next, the iconic stairwell. Or in this case, ramp. I first created a cube and Scaled it into a rectangular block. Then in the Header bar of the 3D view, I switched from Object Mode to Edit Mode - from there I could select Edge Select, which looks a bit like this:
After a little trial and error, turns out the option I wanted was [Delete] and select Edge Loops. Like so:
With my wedge built and placed where I needed it, I created another small Plane for the first landing. In turn, I now had the perfect asset to finish the stairs with, so I selected my wedge again… and found my small Plane was now grafted to it:
Whatevs. I’m going to need a ledge up there anyway. So two Duplicates later:
Of course, this hall now has wings:
Still, for a noob like me, not a bad start. Now onto the rest of the upper floor.
I felt the first set of Planes were a little wide:
So I trimmed them back a bit:
Finally, the door frames. For the sake of speed, I figured I’d make one archway and Duplicate it, which started with a Torus with a small number of Vertices, followed by a bunch of Vertex selecting and deleting:
Until I had this:
Add a couple of Cylinders with a corresponding number of vertices and boom - Duplicateable doorway:
And Duplicate, of course, I did:
Now where’s my lockpick…?