I think I'll opt for Morley Park Manor as owned by my GGGGGG-grandfather Thomas Coppard. Well, I can dream, can't I?
As for smaller things, I'd love to find the only photo of my great-grandfather Charles Adam Willis which hung on the family wall. The only copy of it in existance (as far as anyone knows) was a tiny, tiny little photo taken of the wall which showed it.
Or my granddads little blue BMW Isetta!
Glen