In the Somme basin, one often sees small circular enclosures and small square enclosures on the same site. These funerary sites are either contemporary with each other, or are from different periods. Excavations carried out in recent years, mainly in the Aisne valley (Pommepuy 2000) and in the Ardennes (Lambot 1996), have confirmed these hypotheses. In the early Iron Age, cremations gradually outnumbered burials. Rarely, enclosures surrounded them, as in previous eras, and only the graves of the wealthy were ringed with a circular ditch.
In the late Iron Age excavations attest to the continued presence of circular enclosures that are sometimes surrounded by a palisade, such are those in the Aisne and the Marne, among others, in which rich "chariot tombs" are sometimes placed in square enclosures. We do not know why this brilliant culture of "warrior princes" gradually disappeared during the course of the third century CE.
"La Frénésie" (Pas-de-Calais). The circles are Bronze Age sanctuaries. The square, barely visible, is a sanctuary from the Iron Age. The large dark lines correspond to the perimeter of a Gallic farm.
A square enclosure near two scarcely visible circular enclosures near the trees. One can also see a great many of filled-in pits of all sizes. St Vast-en-Chaussée (Somme).