In the Herbert short story The Road to Dune, Paul’s Imperial Palace, larger than several cities (seriously, the Reception Hall is described as having > 5.4km-high lower roof beams), is described - that was erected in Arakeen in, at most, 12 years, and possibly quite a bit less than that. Constructing that took manpower and resources from thousands of worlds, but (given this is the Dune universe) would not have used robots or nanotech. They do have antigrav, which would help a lot, but it was still a manual labour-type thing.
And how’d that work out for them? 
To be fair, no one rode in a V-1 or a V-2. I was thinking of the Komet. I think the plane itself killed more Komet pilots than the RAF and AAC combined. It was a composite aircraft, with laminated wood. “here, Isaac, use this watered down glue. They’ll never notice!” Plus the fuel itself could and did kill pilots on the ground. No one could probably be sure it was sabotage and not just random failures.
The Me 262 worked out quite nicely in actual combat.
Of course I know that! Flown by Hanna Reitsch. They have a real one and her story at the Kansas Cosmosphere. Never actually entered service though.
Trust the straight dope denizens to know the most obscure facts.