The construction of the first church or cathedral in Coutances in the 5th century is credited to Saint Ereptiolus, traditionally also the first bishop.

The site lay waste for about 150 years but, in the mid-11th century, Robert, bishop of Coutances, undertook the rebuilding of the cathedral in the Romanesque or Norman style, starting with the nave.

Robert died shortly afterward, but the work was carried forward by Geoffrey de Montbray, his successor as bishop, appointed in 1048.

Geoffrey was on good terms with William, Duke of Normandy (later known as the Conqueror), who attended the consecration of the new cathedral in 1056.

The cathedral was used successively as a theatre, a grain store and a Temple of Reason, but despite the losses and damage, survived with its structure intact.

The north ambulatory also holds the holy oils (chrism) used during the sacraments of baptism and extreme unction, confirmation, and at the ordination of priests.

The north transept displays a 13th-century stained-glass window showing scenes from the lives of the saints Thomas Becket, George and Blaise.

The floor of the north aisle is laid with medieval tiles decorated with the fleur-de-lys, or lily, the emblem of the French royal family (and a symbol associated with the Virgin Mary).