ievaulx Abbey was founded in 1131 as the first Cistercian abbey in the north of England. It was a daughter house of the French abbey at Clairvaux. The first abbot was William and he and his twelve monks were granted land by Walter l'Espec. Very soon after its foundation, Rievaulx was sending out new missions to set up new abbeys at Melsore, Warden, Dundrennan and Revesby. The abbey was built on the side of the river Rye. Land on the other side of the river was owned by Roger de Mowbray, and he donated his lands to the order of monks know as the Savigniacs. The Savigniacs built their abbey and called in Byland. The closeness of a second abbey became a problem because each could hear each others bells and so the Byland group relocated their site. The course of the river meant that the amount of land that Rievaulx had in the valley was limited, and so with an agreement with Byland, a new channel was cut and the river was diverted. Normally abbeys are built on an east-west axis, but at Rievaulx restrictions meant that the main axis of the church is almost north-south. Rievaulx Abbey is now in the care of English Heritage and is open to the public.