It was designed by Richard Cailbuilt and opened in 1857 to carry the Bishop Auckland to Durham City railway line across the River Wear and the Newton Cap Bank that leads down to the river. It has 11 round arches, each spanning 60ft, is 105ft high, 828ft long and its foundations had to be sunk 20ft into the riverbed because of the unstable nature of the ground.
The last train to cross it did so in 1968 following the falling of the Beeching Axe and the viaduct fell into a period of disuse and was at one point threatened with demolition. Durham County Council bought it in 1972 and with neighbouring Skirlaw Bridge proving increasingly dangerous for modern heavy traffic, the council wanted to demolish the viaduct and replace it with a road bridge.
But the people of Bishop Auckland rebelled, and the Battle of Newton Cap was fought throughout the 1980s. In 1987, the people won, and the viaduct was saved. Work eventually began converting it into a road bridge in 1994. A reinforced concrete slab was lain across its deck and, when it reopened on July 21, 1995, it had cost £5.85m.
It was the first time a rail bridge had been converted to a road bridge in Britain - although even today it requires help from its 600-year-old partner in times of gales.