Strata Marcella Abbey, or Ystrad Marchell, was once the largest Cistercian monastery in Wales. It was founded by Owain Cyfeiliog in 1170, and building work continued on the site until the early fourteenth century. In 1400-5 the abbey was partially destroyed during the Owain Glyndwr risings, and though the abbey remained active until the Dissolution it never fully recovered from these events.

The monastery was emptied of all items of worth immediately before the Dissolution, after which it was almost entirely dismantled, with the stone being utilised in the building of nearby churches. The site of the former abbey is now farmland; the fields which are regularly ploughed show little indication of their history, but earthworks are still visible in aerial photography of the adjoining fields.
The site was excavated in 1890, and it has therefore been possible to construct a plan of the cloister and church. Many charters survive to attest to the extent of the abbey's landholdings, and these are now preserved in the National Library of Wales (NPRN 23293).

Source: RCAHMW Inventory Documents

K Steele, RCAHMW, 24 November 2008