Attaching the barn to the "foundation" was accomplished by a peg.

I used pressure treated 8"x8"'s on top of rebar reinforced concrete for a foundation. I plan on having hay on the second floor so I didn't want all that weight to cause a settling problem. A perimeter frost wall and piers would have used more cement and I didn't want the horses constantly chipping their hoofs when they used their walk-outs.