So, I'd followed the "Space marines" thing as far as the Wikipedia article on Robert* Anson Heinlein and been diverted, as I often am, to the Google Maps view of his self-designed home off Bonny Doon Road. It is recognizably the original for Jubal Harshaw's house, albeit on a slightly smaller scale.
I'd turned on "photos" and was zooming out, hoping someone had posted street-level views of the place, when a couple of long, straight lines caught my eye, one with a photo thumbnail atop it: it's the "Coast Dairies (?) Conveyor Belt," carrying limestone to a cement plant on the coast. The quarry appears to have been locally contentious and I'm not even sure it's still operating, but you do have to wonder how the man who wrote The Roads Must Roll decades earlier took to having such a long moving way right there on the other side of a hill or two.
(ETA: Beseems I must explain that "decades earlier" refers to the relative chronology of story and house, the latter having been built long after the story was published. Written, I think, during RAH's first California sojourn. The Bonny Doon home was built after their leaving the Colorado Springs house -- Mrs. Heinlein not doing well a mile up and neither of them entirely pleased that their miles-from-any-target home was, of a sudden, sharing Cheyenne Mountain with a very tempting target indeed. What good is that nice fallout shelter at Ground Zero? Anyway, I thought this was clear enough from context....)
* If one's own first name happens to be "Roberta," it is all but impossible to type "Robert" without having to invoke the backspace key.
YANKEE RADIO TOOL KIT, #106
11 hours ago