Lets say you had the gold to build a ten story, 136 room castle would you be allowed to do it? Or will Bethesda have a limit of how much to prevent the game from crashing.

I'm sure there will be limits. I doubt you can build two of any kind of room. I'm guessing you can't have 2 observatories, or 2 gardens, or 2 living rooms. So, once you build one of every available room, the house will be done. I bet you can probably build dozens of bee-houses though.

We wont know till tuesday.

Whats happening Tuesday.

Its being realesed...

I'm betting there will be a limit to how many rooms you can have and some rooms you'll be able to have more of than others. For example bedrooms, you may be able to have 3 or 4 bedrooms but only one kitchen. I'm betting you'll be able to have one kitchen, one alchemy lab, one enchanting lab, one living area plus up to three or four bedrooms. You may also get a few extra rooms but I'm guessing that it will follow that general layout.

So best case scenario is I get it 30 days from then.
Worst case scenario is I get it when Dawnguard is finally debugged, which will probably happen about 15 years after ES VI is released.