Darlington is an industrial and market town in County Durham, located on the River Skerne, a tributary of the River Tees, in the south of the county. Long serving as a market centre for a rich agricultural district, Darlington began to develop as an industrial town when the Stockton and Darlington Railway, the world's first public steam-hauled railway, was opened through the town in 1825 (although the name suggests otherwise, the line did not terminate in Darlington, but extended westwards to tap the coalfields of south-west Durham). Iron works and manufacturing works were set up in the town, and later a major locomotive plant was established there. Darlington has benefitted in modern times from its good communications. It lies close to the main A1 road between London and Edinburgh and on the East Coast Main Line railway linking the two cities; Durham Tees Valley Airport lies within the town's boundaries. Darlington's railway heritage is celebrated by a railway museum at the town's North Road Railway Station (dating from 1825), and by a large brick sculpture, 'Train', showing a streamlined A4 locomotive of the interwar years. Ironically, this is not situated alongside the railway but adjacent to the town's ring road.