Marlin,
In my case, it was the seller (former contractor who managed to lose his license.....wish I had known that little tidbit BEFORE we signed the papers!) who built this building at least 34-40 years ago. As I stated above, I believe he is now pushing up thistles somewhere...... so no recourse.
I found some numbers at the end of the roof I-beams, "4572" which are either a job number, or possibly a date.... 45th week of 1972. I don't work in the industry, so have no idea.....! Varco Pruden was the mfgr.
I think he had some of the construction done to spec, ie concrete was supposedly inspected......and then just never completed the permit process.......to keep it off the tax rolls......he was a tight ass bastard!!!
OR, the county lost the paperwork.
Since this building was professionally designed and erected, we live in an AG active zone, and due to the timeframe dating back to the wild wild west of expansion here, AND we've been paying taxes on it......I doubt that anyone would go to the trouble of requiring that I tear the building down. Not good press nor good for their tax roll!
If it came to that point, as soon as the last piece of old concrete was hauled off, I wheel in 10+ 40' storage containers and weld them all together, put a canvas roof over it to avoid calling it a permanent structure..... and be happy! 
Cheers!
Steve