Fasinating old film of the construction of boulder dam. https://www.youtube.com/watch?v=PSMDPzd11ek
I found it of special interest because I have/had actually met the head engineer of the project for Six Companies, Frank Crowe.
He and Six Companies moved on to build Shasta Dam in Northern California after they finished Boulder Dam and it is there that i met
him many years after the dam construction.