The Chetwynd Viaduct has stood in this condition since 1961, when the line it served was closed, and the silence up there now is the kind that makes the engineering feel all the more improbable.

The structure was completed in 1849 for the Cork and Bandon Railway, one of the earlier regional lines to push through the south of Ireland during the railway boom of the 1840s. Each of the four spans measures 33 metres, and the combination of materials, wrought iron and cast iron for the spans themselves, dressed limestone for the supporting pillars, reflects the construction thinking of that period, when engineers mixed the two forms of iron deliberately: cast iron handled compression well, wrought iron was better suited to tension. The result at Chetwynd is a viaduct that managed both the height and the breadth of the crossing with a degree of confidence that still reads clearly in the structure today. The Cork and Bandon Railway eventually became part of a broader network serving west Cork, but when that network was wound down in the early 1960s, the viaduct was left standing without a purpose, too substantial to remove and too old to reuse.