Longues Abbey (French: Abbaye de Longues, Abbaye Sainte-Marie de Longues) is a former Benedictine monastery in Longues-sur-Mer, Calvados, Normandy, France.It was founded in 1168 by Hugh Wac, of a family that owned Rubercy and other lands in the Cotentin, and was generously supported by gifts from the English and Norman nobility, and from King Henry II. The prominent families of Bacon of Molay and d'Argouges were particular benefactors of the abbey and several of them were buried there. Numerous ruins and structures remain, which have been listed at various times as monuments historiques.