Whilst searching for a Hirst Arts ruin that was skulking about in my memory, I uncovered new inspiration. A day or so later, this little crumbling beauty debuted on the table:
Here it is with a skeletal guard, and then with my four D&D B/X heroes:
I cobbled together some scenario objective markers using some old Games Workshop plastic skeletons. A bit of surgery on the pelvises allowed them to sit or lie, suitable splayed.