Viaduc de Chapeauroux, Railway bridge in Saint Bonnet-Laval, France

The Viaduc de Chapeauroux is a single-track stone railway bridge over the Chapeauroux valley at the hamlet of Chapeauroux, in Saint-Bonnet-de-Montauroux. Its 28 natural-stone arches, each 12 m wide, carry the deck 433 m along a curve of 260 m radius, with a low parapet along the top.

Work began around 1857 for the Compagnie du Grand Central, but its bankruptcy halted the site; the PLM took over in 1862 and entrusted engineers Dombre, Ruelle and Joubert with the design. Contractors Marigues et Ramon completed the viaduct in early 1870, and the line opened on 16 May 1870. The structure has been a monument historique inscrit since 28 December 1984.

The viaduct stands as part of the Cévennes railway line, demonstrating French engineering capabilities in mountainous regions during the nineteenth century.

The bridge is accessible from pathways that let visitors view the structure from various angles. The best view comes from the riverside, where you can see the full shape of the construction.

The construction site uncovered remains of the Gallic village of Condate, whose name means "confluence", at the meeting of the Allier and Chapeauroux. Condate was one of three stations of the via Agrippa in Gévaudan and appears on the Peutinger Table alongside Anderitum and Silanum.