Burnt several times, damaged and totally destroyed during the First World War, the present church was inspired by Romanesque and Byzantine styles.
As the building is imposing, it is referred to widely as the “cathedral of the Lys” even though it is not the seat of a bishop.
The Art Nouveau furnishings are in flamed ceramic, notably the high altar, the communion table, the pulpit and the confessionals. Noteworthy also are the fine oak stalls (1714) which came from the ancient abbey here.
The crypt contains the tomb (14th century) of Robert de Cassel , son of the Count of Flanders.