Also a system to place beams that perhaps take up space, a better option for a 'stone' building more similar to castles perhaps?

I know castles don't belong and I want nothing like that infamous screenshot, but I would want to create an epic 'building' akin to a castle.
Also if added 'floors' to buildings shouldn't be allowed in mines? Perhaps different types of buildings for mines in general?
Mine buildings might be something to put off a long time until mines are redone but they could double as storage and keeping up the roof from cave-ins for quite some space.