Pont Antoinette, Railway arch bridge in Sémalens, France.

Pont Antoinette is a masonry railway bridge over the Agout between Sémalens and Vielmur-sur-Agout. Its single segmental arch has a 50 m span and rises 11.50 m above low water; the arch is faced with pale stone, while the rest is built of Beaucaire stone, Sidobre granite and Albi brick. Above the arch, five brick round arches on each side carry the 89.25 m deck.

Engineer Paul Séjourné designed this structure in 1884 as part of France's railway expansion during the 19th century. The project was built when France was rapidly extending its rail network across regions.

Locally the bridge is called pont de l'Aiguillou, after the neighbouring farm, though Séjourné named it for his wife Antoinette Lesueur de Pérès. A model of the bridge, showing his wooden centring, is displayed in a window of the Arts et Métiers metro station in Paris. The Albi brick facing gives the structure its reddish colour.

The bridge is inspected and maintained regularly to safely carry trains and vehicles. Visitors can view the structure from the Agout riverbanks or from nearby roads that provide clear views of its design.

A scale model of the Pont Antoinette is displayed in a window of the Arts et Métiers metro station in Paris, showing Paul Séjourné's wooden centring system. The bridge's arch was built in successive rings, each serving as centring for the next.