I recall reading about structures similar to the "henge" that were found as the Red Army advanced into what had been Nazi occupied Ukraine and eastern Poland. The structure in Ukraine was apparently mostly destroyed, but the one in Poland was surrounded by hastily abandoned buildings that contained what appeared to be engineering workshops and administration blocks. The installation also had its own localised power generation system and was surrounded by what had been substantial multi layered defences. The most interesting aspect - for me anyway - was the "henge" itself. It was somewhat smaller than the one in the video, with the horizontal cross beams at the top supporting a huge copper ring. There were signs that a huge amount of current had been fed into the assembly too. The mind boggles. The Nazis were up to all kinds of weirdness.