Beatrix replies, [color=blue]"Unfortunately, with Günther's size, I will need a differently shaped sanctum than any of these. I can provide the vis for your spell, and I can cast a 4th-magnitude Wizard's Communion for my own and to assist with the others. We can discuss the details of the building privately so as not to take up everyone's time."
(OOC - Only one magus in Communion? With Bea's 20 levels, and presuming this spell is 35th level, 50 more levels of Wizard's Communion are required. I highly suspect that will take at least one more in addition to these two. Fortunately, it looks like there might be a few magi involved.)
A some point a little later Bea discusses the construction with Eilid. It would be 3 floors of 2000 square feet each (just over 25' radius or 50' diameter) with a 7' thick foundation. (That is based on Conjuring the Mystic Tower's dimensions.) A slightly domed roof to deal with snow would probably be good. The third floor would actually be a little smaller on the inside with a balcony around most of it, so that the inside plus balcony have the same footprint. Of course there are some interior details (antechamber in 3rd floor, rooms for different people in the first floor, etc.), but writing it all out here seems a pain. Bea isn't concerned with the location so long as it is solid and within the good aura.
(OOC - Anyone have good suggestions for a good, free drafting program for Mac OS X, one that will do such floor plans nicely? That would be a lot easier that writing it all out.)