Château d'Avranches, Castle ruin in Avranches, France

Château d'Avranches is a former fortress on the promontory above the Sée and Sélune confluence, of which only ramparts remain. The surviving round Arsenal tower, also called Saint-Louis, stands behind the town hall on rue de la Belle Andrine: rough grey-brown masonry, a crenellated parapet on corbels and two carved shields. A curtain wall with a flat crenellated top runs beside it, pierced by small openings and loopholes.

The site was occupied by the Abrincates, then the Romans, Saxons and Franks before the castle was built around 950 under the influence of Onfroy le Dane, whose keep has left no trace. Archaeology places this stonework among the first fortifications in Normandy, alongside the towers of Rouen and Ivry-la-Bataille. The visible ramparts date from Duke William of Normandy; Louis IX later bought the place and rebuilt the fortress after Guy de Thouars burned the town in 1203.

The castle's name comes from Avranches, the town it once guarded above the Sée and Sélune confluence. The site had earlier been occupied by the Celtic Abrincates, then the Romans, Saxons and Franks. Today the surviving ramparts stand near the former cathedral of Saint-André and the place d'Estouteville.

The surviving ramparts stand around the site of the former Saint-André cathedral and along place d'Estouteville, where the Arsenal tower and the Geôle tower remain. The Arsenal tower, behind the town hall on rue de la Belle Andrine, is listed as a monument historique. The promontoire overlooks the Sée and Sélune confluence and the Mont-Saint-Michel bay.

The castle stood at the tip of the promontory above the confluence of the Sée and Sélune rivers, a position chosen to watch over the Mont-Saint-Michel bay and guard the south-western border of the Duchy of Normandy against Breton incursions. The surviving Arsenal tower, also called Saint-Louis, is listed as a monument historique.