Chiesa San Martino, Romanesque parish church in Arnad, Italy.

Chiesa San Martino is a Romanesque parish church in Arnad featuring rounded arches and thick stone walls typical of the period. The structure displays characteristic architectural elements with simple geometric forms and substantial masonry construction.

A chapel of a Benedictine monastery of Fruttuaria stood here in the 9th century; its foundations survive in the central apse. After a flood destroyed the parish church of Saint-Germain d'Auxerre in the 11th century, the chapel was rebuilt as a three-nave basilica. In 1181 the Benedictines ceded it to the prior of Saint-Gilles at Verrès. Giorgio di Challant promoted the late-15th-century vaults and tufa portal, and restorations in 1949–52 removed most Baroque additions.

The tufa portal shows two intertwined tree trunks, read as the marriage of a Vallaise baroness of Arnad and a Challant count of Issogne, nephew of prior Georges de Challant. Inside, the left chapel was built by the Vallaise barons and the right one by the Rosary Confraternity. Near the right chapel's wooden altar stands the parish museum, with wooden statues, reliquaries, vestments and liturgical books.

The church welcomes visitors during services and can be viewed from outside at any time. For specific opening hours and access details, it is best to check with local information sources in Arnad.

The best-preserved frescoes, attributed to the anonymous "Maestro di Arnad", are hidden in the space between the roof and the vaults of the left nave and are normally closed to visitors for safety reasons. They show Saint George and the dragon, the Banquet of Herod, the Apostles, a Crucifixion, Saint Maurice on horseback and the Martyrdom of Saint Stephen. The same painter also worked on the exterior right wall, where a Mass of Saint Gregory and large figures of Saint Christopher and Saint Peter flank the side door.