Firefighters left Illinois' oldest round barn to smolder Friday after a nearby bonfire set the dilapidated building ablaze. The owner of the property at 25208 River Road, Marengo called 911 at 10:51 a.m. Friday, after learning the vacant structure had caught fire, officials said. Marengo and Union fire departments responded to the call and extinguished the fire outside of the barn, Marengo Fire Battalion Chief Noel Gaines said.