St Martin church was erected during the 12th century on a rocky promontory overlooking three meanders of the Rance River. The church dedicated to St Martin was for the most part built in the Romanesque style, namely the choir and the transept. In contrast, the original nave was later enlarged in a Gothic style. The building which has an octagonal bell tower is visible from a great distance, and you can't miss it from wherever you might come. This church appears like a watchdog supervising the Rance valley and its illumination at night makes it a landmark.

From the 19th century porch, one can access to the inside of the church through a Romanesque style door which is the only remaining part of the original 12th-century nave.

On the left side of the entrance, stands a 15th century cross of the Hospitallers of Jerusalem. A fleur-de-lys and a Maltese cross ornament this cross which comes from the ancient Hospitallers Commandery of St Laurent, a hamlet situated in the heights of the municipality. This Commandery was later transferred to Martrin. The cross was taken back to the church of Plaisance. In contrast, a replica was set in St Laurent where it had been originally located.