Meanwhile, I find this more interesting: https://en.wikipedia.org/wiki/U.S._Army_Corps_of_Engineers_B...
The Army Corps of Engineers literally built a scale model of the San Francisco Bay Area, and they used it to figure out that damming the SF Bay was a very, very bad idea: https://www.youtube.com/watch?v=i70wkxmumAw
In the absence of accurate computation modeling (either hardware or physics models) in the 1940s-70s, it's a pretty ingenious way to simulate complex hydraulic systems.
And as for Atlantropa, think about it in these terms: (a) a large, funded public-works program in Europe, just as the Nazi Party was gaining support and before the Spanish Civil War, (b) substantial amount of cheap, carbon-free energy for Europe and North Africa by now, & (c) a pan-European effort ~50 years before most EU structures.
You'd have a hard time convincing me that would have been doomed to turn out worse than actual history.
[0] https://en.m.wikipedia.org/wiki/Mississippi_River_Basin_Mode...
It's interesting that the Mississippi model's scale was specifically chosen to minimize unrealistic effects of surface tension, that might have dominated at a smaller scale. (But it was the 1940s, and I'm sure we know more about surface tension and hydrodynamics now)
Off topic, is there a reason why comments do not support HTML anchor elements?