The Middlefield Banking Company Share: BanksFinancial ServicesMortgage Lender The Middlefield Banking Company Visit Website 490 S Jefferson Ave Plain City, OH 43064 (614) 689-2622 (888) 801-1666 Facebook Hours: M - Th 8:30 AM - 5:00 PM Fri 8:30 AM - 6:00 PM Sat 8:30 AM - Noon