This Flamboyant Gothic church (15C-18C) is architecturally harmonious. Its very slender slate spire is crafted in an original style. The chancel has a wealth of 18C wood panelling and the side chapels house 15C granite altarpieces. In the left chapel, in the centre of the altarpiece dedicated to Anne of Brittany, its donor, the statue of Our Lady of the Marshes is highly venerated. It is said to have been found near the castle in the surrounding marshes around 1300.