The old cathedral was constructed almost entirely in the 13th, 14th and centuries. A heavy square tower finished in 1499 surmounts the west portal. The church contains Biblical paintings, a colossal statue of Christ seated between the Virgin Mary and St John (13th century, originally belonging to the cathedral of Thérouanne and presented by the emperor Charles V), the cenotaph of Saint Audomare (Omer) (13th century) and numerous "ex-votos". The richly decorated chapel in the transept contains a wooden figure of the Virgin (12th century), the object of pilgrimages. Of St Bertin church, part of the abbey (built between 1326 and 1520 on the site of previous churches) where Childeric III retired to end his days, there remain some arches and a lofty tower, which serve to adorn a public garden. Several other churches or convent chapels are of interest, among them St Sepulchre (14th century), which has a beautiful stone spire and stained-glass windows. The cathedral has a huge Cavaillé-Coll organ, which is still playable.