Yeah, that’s my conclusion as well. Lack of windows means no electronic interrogation, monitoring, interference and maybe (?) designed to withstand some sort of EMP attack? (dunno)
I assume those massive openings can be buttoned-up inside somehow - just a guess, of course
Windows are a huge source of neat loss. Since nobody and nothing needs natural light inside the buildings, no need for windows. Plus, as you say, it makes it a lot easier to shield all the data equipment inside a huge Faraday cage.