Only a fragment of the western portal and the line of the walls remain of this Cistercian abbey that was founded in 1164. Cistercian ideals of simplicity and poverty went better with the Welsh temperament than the Benedictine rule. Strata Florida, completed in 1201, became one of the main centres for culture and Welsh influence. This is where Llywelyn the Great assembled all the Welsh princes to have them swear allegiance to his son Dafydd.