Chapelle Saint-Gildas de Bieuzy, 15th century Catholic chapel in Pluméliau-Bieuzy, France

Chapelle Saint-Gildas de Bieuzy is a chapel built partly into the rock, positioned beneath a granite formation along the Blavet River with two sections arranged in line. Both areas are built from granite and quartz materials, creating an unusual structure that fits naturally into the surrounding stone.

According to legend, Saint Gildas and his disciple Bieuzy settled in a cave by the Blavet in 538, and monks from Rhuys Abbey later came to join them. The present semi-troglodytic chapel is documented only from the 15th century, when it became the priory of La Roche-sur-Blavet, dependent on Rhuys until the French Revolution. The south wall was rebuilt in 1810 and the chapel lengthened westward in 1837.

The chapel holds two stone altars dedicated to Saints Gildas and Bieuzy, with 19th-century polychrome plaster statues of the two saints. Outside, a rock-cut 'chair of Saint-Gildas' is where the saint is said to have preached, and the fountain below it is traditionally credited with curing infertility.

A hiking trail connects Saint-Nicolas-des-Eaux to this chapel, with parking available around 200 meters away. Visitors should wear good walking shoes since the path goes over rough terrain.

The sounding stone is not inside the chapel: it lies on a granite base outside, sometimes at the foot of the outdoor stairway to the "chaire de Saint-Gildas". Struck with the pebble kept beside it, this porphyritic or hornfels rock rings almost like an anvil or a bell; legend says Gildas used it to call the faithful. The stone itself was listed as a historic monument on 12 May 1981, and a smaller second one is kept in the Notre-Dame church at Bieuzy.