unitary authority, geographic and historic county of Lincolnshire, England, comprising a low plain on the south shore of the River Humber estuary that extends inland to the northernmost Lincolnshire Wolds and the reclaimed wetlands of the Isle of Axholme (Axholme, Isle of) along the River Trent. The unitary authority covers a largely rural and agricultural area. Its fertile lands produce heavy yields of cereals, sugar beets, and vegetables. The unitary authority is also an important industrial centre, with two major oil refineries at Killingholme on the Humber, a large steel mill at Scunthorpe, and other industries, including food processing. Scunthorpe is North Lincolnshire's largest town and administrative centre. Among the area's historic landmarks are Normanby Hall, a Regency country mansion completed in 1830, and the Old Rectory, the childhood home of John Wesley (Wesley, John) in the village of Epworth. The Humber Bridge—the longest suspension bridge in the United Kingdom, with a length of 4,626 feet (1,410 metres)—connects the unitary authority with Kingston upon Hull and the East Riding of Yorkshire. Area 328 square miles (850 square km). Pop. (2005 est.) 157,100.