I never quite understood why domes really didn't take off in old Rome.They already had the fundamental units well understood and in use, being the arch and the vaulted ceiling.

Sadly, DG, my best hopes will be in the sandstone of the west side of the central part of the Spring Mountain range out here. Finding a relatively small mouthed cave, closing it off and carefully hand mining it out, using the "tailings" for connected outbuildings... something along the lines of the Pueblo Indians' constructions, now that I think on't.