Cymer Abbey was founded in 1198/9 and dedicated to the Virgin Mary, under the patronage of Maredudd ap Cynan, Lord of Merioneth and grandson of Owain Gwyned.

While Cistercian Orders were by their very nature secluded and austere, Cymer was notably poor, in part due to the Welsh Wars of Edward I (1276-77 and 1282-3), and thus the considerable remains of the church and tower are conspicuously plain. The original design for the church was never completed; it does not conform to the standard cross-shaped plan, lacking northern and southern transepts, and the choir and presbytery, originally intended to lie to the east of the building, were incorporated into the nave. Plans for a central tower were abandoned in the fourteenth century, replaced by the unusual western tower. The abbey features buff sandstone dressings and some red sandstone carvings, but is primarily of crude local rubble and boulder construction.
To the south of the church, only foundations remain of the cloister and claustral buildings. The abbots' lodgings (NPRN 3048) and abbey farmhouse (NPRN 28142), both extensively restored, remain to the west of the site in what had been the outer court. After the dissolution the immediate lands of Cymer were integrated into the parish of St Illtyd's Church, Llanelltyd (NPRN 43876).

Source: Robinson, David M. 1995. Cymer Abbey: Cadw Guide (Second Edition)

K Steele, RCAHMW, 7 November 2008