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My wife's grandfather designed buildings like that in the 1960s for the Ministry of Defence in the UK. They had special wall and ceiling coverings, artificial floors and were lined with RF shielding even back then. They had an immense list of engineering checks that had to be done right down to light transmission.

One of the really cool things is they had developed a method of determining what keys were pressed on a typewriter by the sound back then (these were IBM ones so this wasn't hard) and had to design ways for the sound to be dampened enough to not reveal it outside of the communications rooms. Even things like heating pipes were carefully dampened.