As long as someone doesn't do something really stupid in the near future, depending on the facility manager (some are too lazy to do the work or have it done to get the clearances.) if you are a pilot or controller and want to visit an ATC facility, it can be done, but takes a LOT of coordination and information. They then send the info to Washington DC to have a background check done and then give approval or not. I just got one done here for someone... (they didn't show up <sigh>)
So yes it is possible, but your answers to the question vary from place to place...
regards
Scott