The Monts Caubert oppidum at Mareuil-Caubert (Somme) is poorly preserved. It was occupied many times, notably by English troops during the Battle of Crécy, and then in 1940, where it was the scene of fighting.
In the Middle Ages, mounds of earth were sometimes constructed inside and on the rims of oppida, like at l'Étoile (Somme).
The strategic location of the oppidum at Chipilly (Somme) is remarkable. It is built on a hill, cut in two by earth levees. One is still visible above ground level, and the other has been leveled.
The oppidum at Etrun-sur-Escaut (Nord) is elliptical in shape. Excavations have proved that it was Gallic in origin, even if medieval sources state that it was built by Louis III. In reality, he simply reoccupied it.
The most characteristic of the oppida of the plains is the one at La Cheppe (Marne), located on the banks of the Noblette River. It is well preserved, entirely of human construction, and nearly circular in shape. It is ringed by a an enormous rampart and large ditches.