Tintern Abbey, ecclesiastical ruin in Monmouthshire, Wales, on the west bank of the River Wye. Founded for Cistercian monks in 1131, Tintern Abbey was almost entirely rebuilt and enlarged between 1220 and 1287. The building was finally completed, except for minor additions, in the early 14th century. The abbey was dissolved in 1537, and its property was granted to the lord of Chepstow; the crown bought it in 1900. Although the cruciform church is without a roof and the nave is damaged, many details of a style transitional from Early English to Decorated Gothic are preserved. Cloisters and other monastic buildings are placed unconventionally to the north of the church. The ruins of the abbey were made famous by William Wordsworth in the last poem of Lyrical Ballads (1798).