A first church was built to house the remains of Florus, a bishop of dubious historicity and first legendary apostle of Upper Auvergne.
[2] In the 11th century, Odilon de Mercœur, Abbot of Cluny built a Romanesque basilica that Pope Urban II consecrated in 1095 under the triple name of Saint-Sauveur, Saint-Pierre and Saint-Flour.
Bishop Hugues de Manhac oversaw the reconstruction in spite of a difficult situation (Hundred Years' War, plague).
A new, Gothic cathedral with three naves and four towers (two on the west and one on each side) was consecrated by Bishop Antoine de Montgon in 1466.
Between 1846 and 1856, important restoration work was undertaken under the leadership of Monseigneur de Marguerye, bishop of Saint-Flour.