As if stranded on their limestone foundations, the gaunt ruins of the chateau d'Arques are testimony to the evolution of the castle architecture over five centuries. From the mid-eleventh-century fortress built Guillaume d'Arques I, there remains only the main enclosure, a vast oval ring originally devoid of any flanking masonry. The addition to the enclosure of the main tower and the porch tower around 1125 may be attributed to Henri Ier Beauclerc. The flanking was added progressively during the reigns of the Plantagenet kings, between 1154 and 1204, and completed in 1204 with the elaboration of the south front, which received three archers towers, as well as a defensive sheath hollowed out mid-slope in the scarp of the ditch, foreshadowing Anglo Norman undertakings of the thirteenth century. The thirteenth, fourteenth and fifteenth centuries do not appear to have brought any new constructions to the masonry corset already in place between Philippe Auguste conquered Normandy. There are many remaining accounting records, however, that attest to the regular upkeep of the castle, insuring the maintenance of its defensive potential, especially the high timbered defenses. Progress in artillery motivated timid attempts in the second half of the fifteenth century to adapt old defences to the new weapons. The main tower was covered with a masonry terrace supported by ribbed vaults, arrow slits were converted into canonry loopholes, and the structure of wooden brattices was reinforced. In 1513, a Bollevert de terre was constructed, forming an outwork in front of the south access to the castle. During the first quarter of the sixteenth century, the construction of four large artillery towers, in place in the old northern outwork, constituted the last phase in architectural evolution of the castle. The natural prominence of the site, which was its strength in the Middle Ages, rendered the fortress unsuitable to the requirements of bastioned architecture, which was based on the principle of a defilading profile. Following an on-the-spot inquiry led by a royal officer in 1706-1708, the fortress was declared unsuitable for service to the King. Because of their state of decay, the constructions visible today, some of which still need to be stabilized, elude traditional methods of architectural analysis. The chateau d'Arques remains no less a site of major interest both for the vision that it offers of the reappearance of enclosure flanking during the Platagenet period before 1204 and as a rare example, represented by the outworks in brick on the north face, of an architecture in transition in the years 1500-1525, between medieval and bastioned fortifications.
