I think the most impressive part about these sites was the way they networked them together with UHF/Microwave Troposcatter links, which basically just scream RF into the sky and then listen for the small amount of energy that's reflected off the troposphere on the other end. (It's a little more complex than that)
This method was the back-bone of long distance Cold War communications links (As well as HF using ionospheric propagation) until Satellites started becoming more commonplace in the 70's
https://en.wikipedia.org/wiki/Tropospheric_scatter
This method was the back-bone of long distance Cold War communications links (As well as HF using ionospheric propagation) until Satellites started becoming more commonplace in the 70's