A Grade II* listed, five-span skew arched viaduct built in 1836-40 for the North Midland Railway. The viaduct forms part of a series of railway structures built for the North Midland Railway between 1836 and 1840. The line was designed by George and Robert Stephenson, two of the most important and influential engineers of the railway era, aided by Frederick Swanwick, the company's resident engineer. It is considered to be one of the best preserved examples of the pioneering phase of railway development in England, and retains many of its original engineering structures. The structure is one of the few surviving stone viaducts on the line and exemplifies the architectural flair with which the Stephensons applied themselves to engineering challenges. Cutting-edge developments in skew arches were designed specifically to meet the requirements of the railway, enabling them to be built in large numbers for the first time. Skew bridges represent a truly innovative engineering solution of the pioneering phase of railway development. This outstanding structure was at the forefront of railway engineering in the world. The impressive aesthetic quality of Derwent Viaduct far exceeds its functional and structural requirements. It is a finely composed viaduct constructed of masonry that has been worked to the highest standard, and it demonstrates the consistently high quality design and careful detailing of the railway structures completed for the North Midland Railway. The extension of two piers and an abutment to support a new track were carefully faced with coursed, quarry faced gritstone to minimise the impact of the intervention. This modification has not unduly detracted from the architectural integrity of the viaduct, and it reflects the evolution of the line which has played an important part in forming its character. See list description for more detail. (1)