Marennes-Oléron's religious heritage is rich. There is a church in each district. Some of these churches are listed historical buildings.
Oléron Island counts several Romanesque churches. Such as the Saint-George d'Oléron church built during the 11th and 12th centuries, it is one the oldest on the island. It has undergone building work on numerous occasions throughout the centuries. From its initial structure, two aspects remain intact: the nave and the west portal. It was destroyed by the Huguenots in 1568 and later restored in the 17th century. Nowadays, with its four large columns and recently added oculus, the façade looks wonderful.
Built during the 12th century in the reign of Aliénor d'Aquitaine, Saint-Denis d'Oléron's church had fortifications. The history of this church is an eventful one. Its most interesting features are the remarkable façade, the columns and portal as well as its geometrical designs.
The church of Saint-Pierre de Sales in Marennes was founded in 1047 and rebuilt during the 14th and 15th centuries. It hosts an astonishing 85 metres high gothic bell-tower. The terrace
at the top offers a unique view over the Marennes Basin.
In the Saint-Sornin district, the Romanesque church of Saint-Saturnin built in the 12th century is a real gem. Originally a priory, this monument was destroyed during the Wars of Religion. The bell-tower and the choir were rebuilt at the end of the 14th and start of the 15th centuries with the façade and portal dating back to the 16th century. The large scale renovation work which took place from 1978 to 1988 brought back some of its original features including splendid 17th century frescoes.