I have two words: In sane.
Of course, there was that gutted Reichstag I saw...
There've been some recent BBC documentaries on refurbishing the palace, but I'm not good at noodling the Beeb's site. I'm sure there's footage you could come across, including roof info.
I think most folks assume just the front, on one edge of the table, would be apropos of an approach battle; you could even hang the building from a 'play room' wall, and push the table underneath.
You aren't intending for it to be a 'cutaway' to be able to carry the battle inside, are you?
Doug