@reirab why in the heck would you transmit that knowledge to the next generation if there's (1) no need to build a road or aqueduct, and (2) there are pressing needs to feed yourself and defend yourself against invaders?

@reirab just as importantly, consider this: we don't know how to forge battleship armor anymore. Those skills were lost when we stopped building battleships.

@RonJohn I don't think anyone ever actually stopped building roads. They just didn't continue building them on the scale of the Roman Empire because they no longer had an empire spanning much of Europe and pretty much the whole Mediterranean basin to move troops and supplies within nor the cheap labor that could be organized to build them for such long distances.

@RonJohn As far as "knowing how to forge battleship armor," I don't think I'd completely agree with that, either. We might not have the exact way that it was done in the early 1900s, but it's not like we couldn't do it today if we actually wanted to, likely with significantly better materials than they had back then. Just because we'd do it different doesn't mean we can't do it.

Also, we do still have the plans for at least the later classes of American battleships, including their armor designs. We have blueprints for the Iowas, for example. I would guess that the Royal Navy still has the plans for their more recent battleship classes, too, though I'm less familiar with that.