I didn't know there were condos in 1970 ... though I must have become familiar with that term/concept not too much later than this, because I think it was around 1972 when an aunt of mine bought one ... but I grew up in a smaller town where there never have been condos!
BTW dom, in the earlier thread on this topic (it might have been on the former VantageNet board), I pointed out the hallway or entry outside Stokes' door, which seemed to not be part of his own quarters -- though I think there was a scene at that time where Julia and perhaps Barnabas approached an outside -- as in cold, windy, outdoors -- door and knocked on it when visiting Professor Stokes. That was the only time we saw Stokes' place from the outside (or people knocking outdoors). Every other time, people seem to knock from a hallway or common area.