No it is not in an old CO. It is in a converted ranch style house.
My son used to live in Tacoma. The last time I visited, I talked him into visiting the Seattle museum with me. That place is awesome! Not one, not two, but at least 3 operating switches (SxS, #5 and ESS). And they let you play! Very, very cool. They are only open Sunday mornings, I think. And I will probably never get back there, but they now have a working Northern Displayphone I donated as a thank you.