I've got a 2,000 sq ft barn that is over 80 years old. The foundation is mostly 8x8 timbers sitting on concrete blocks (some on the ground). Rot and settling means this barn will slowly fall down. The wood from 12 inches and up is old growth doug fir and is in great shape. (Today, I just met the barn owl who's bee dropping pellets for years.)
1. Jack it up and pour a concrete foundation, stem wall and floor?
2. Deconstruct it and rebuild just what I want out of the solid materials?
If I do #2, I'll probably turn it into my dream woodshop (I've got my eyes on some 3x6 double t&G fir that would make a great shop floor).
On the other hand, the preservationist in me says save the old barn.