Switching centers have no need for windows! Weak points and EM eavesdropping can occur through them if they are not EM hardened. I used to work in one. Even the windows that are there will have a fine wire mesh in the glass earthed to the frame and there will, in all likelihood, also be a metalised mirrored anti-glare film on the windows too. Windows will probably not be able to be opened as well. Walls on those buildings are usually 18" or thicker with Faraday shielding on every floor. Sounds paranoid; it is and for good reason!