Speaking of open-ness, I feel like I can't even do that here. My latest playthrough I've made a game out of exploring as much as I can, but avoiding certain zones from being marked as visited on my map. I heard that once you visit somewhere, it's scaled to the level you are when you found it?
I have to say this isn't as hard to find out as people are suggesting. Interiors are set at the point you first enter them, not the point you first discover their door. Any enemies on the outside will be set at the time you discovered the location, but they are seperate from the interiors.
To see this in action, visit the fort just west of Whiterun when you are at low level. Avoid going inside for the time being. Ten or so levels later, attack the fort. All the bandits on the outside are low level, all the bandits on the inside are at your current level. Next game, avoid that whole cell until you are at high level, then attack the fort. All the bandits on the outside are the same level as the ones inside (And if youi attck the whole fort at low level, all the bandits inside are at low levels).