I know this can be somewhat ameliorated by the use of HOSTILE, but it
turns a place with multiple buildings into a lot more complex turn --
without really gaining anything.
It might also solve the problem of people who start new construction
being temporarily "invisible" as well--if I start digging a mine and
you come into the province to attack me, you *can't* attack me that
week, because not only can't you get into the mine (protections), but
you don't even have an ID of the mine to try to get into.
The reality drawback to this is towers and castles, where it could be
reasonable to assume that the people inside are -not- generally known
to be there. I'm not sure that this is a good -general- rule, but thought
I'd toss it out for discussion.