Yes Im reading it now. The thing is that I know you HAVE to build castles to tech up, and they might aid somewhat in dealing with unrest, but my only real concern was that castles dont offer complete protection to any of your buildings.

So lets say I have province A and you have province B. My forces in province A could easily resist a castle assult if your larger and stronger army in B attempted an attack.

Turn 1: you attack, a few buildings are downgraded/ruined. I retreat to castle.
Turn 2: you give up the seige after seeing my forces could hold out for years.
Turn 3: you return and attack the province again, I retreat into the castle and a few more buildings bite the dust.
Turn 4: you go home (again).
Turn 5: repeat steps 1-4 until my province is completely depleted of improvements.

The above sequence of events is exactly why I am frustrated with the fact that I cannot rely on castles to resist attacks: if I do, I might as well write-off any hopes of improving any province that shares a border with any enemy.

See my point? Now if the castles protected my buildings as I hoped/suggested, I could focus on castle development in my border provinces and build my level 3 castle before my level 2 buildings to ensure theyd be protected in the above scenario. It is a less-efficient way to tech up but thats the price you pay for the safety!