Douvenant Viaduct, Railway viaduct in Saint-Brieuc and Langueux, France.

Douvenant Viaduct is a railway viaduct built entirely on a curve between Saint-Brieuc and Langueux, in stone and brick. It has 15 arches, each 6 metres wide, a total length of 130.8 metres, a height of 22.8 metres and a curvature radius of 109 metres. Two tiers of arches rise above the valley, with lighter stone edging along the arches and parapet.

The structure was built in 1905 by engineer Louis Harel de la Noë as part of a railway network that expanded regional connections in Brittany. It represents an era when such engineering works were essential for linking towns and advancing transportation.

The structure has become a landmark that reflects how industrial engineering shaped regional identity in Brittany. Today, it serves as a gathering spot for walkers and cyclists who appreciate its role in connecting communities and preserving local heritage.

The best starting point is the Cesson cemetery parking area, where signs guide visitors toward the structure through walking paths. Multiple access points and viewpoints are available along the way, making it easy to explore the structure from different angles.

The viaduct is built entirely on a curve, with a radius of 109 metres, and is the largest of thirteen "grognet"-type viaducts designed by Louis Harel de la Noë. It has 15 arches of 6 metres each, a total length of 130.8 metres and a height of 22.8 metres. Since May 2022 it has carried a greenway on the Vélomaritime (EV4) between Cesson and the Saint-Ilan brickyard in Langueux.