This was the first cast iron bridge on the first public railway ( Darlington - Stockton Railway)  Crossing the River Gaunless  ( River Gaunless believed to be named by the Vikings meaning useless. ) designed by the self taught Engineer George Stephenson and built by John and Isaac Burrell.  It was completed on October 23, 1823 but six weeks later there was a severe snow storms which was so bad that even mail coaches were stuck for weeks in snow drifts at Rushyford.  When the thaw came the Gaunless Bridge became a victim of the swollen river, partially washing it away, so Stephenson revised his plans so that there were four spans inside of his original three. The were held 12` 6" apart by iron girders.  This section of the Darlington and Stockton railway between Bruselton and Etherley inclines on which the bridge sat (bottom of Oakley Green) seems only to have used horsepower and not locomotives.  So when the Shildon Tunnel opened in 1856, it fell into  disuse.  The bridge clung to its supports until 1901 when it was moved to Brusselton Colliery only to be shifted again in 1928 to Queen St museum in York