The Abbey of Strata Marcella (Welsh: Abaty Ystrad Marchell) was a medieval Cistercian monastery situated at Ystrad Marchell (Strata Marcella being the Latinised form of the Welsh name) on the west bank of the River Severn near Welshpool, Powys, Wales.

Building work continued until the early 13th century, by which time Strata Marcella had become the largest Cistercian Abbey in Wales.

[3] Owain's son Gruffyd ap Gwenwynwyn, lord of Powys, entered a monastery when he was close to death about 1260, but recovered during his stay; it is thought that this abbey was Strata Marcella, which was near his seat at Pool.

During the Owain Glyndŵr rising at the beginning of the 15th century the buildings were heavily damaged and the monastery never completely recovered.

[5] Today the only visible remains are a few courses of stones from the church and cloister in a meadow beside the infant River Severn.

The red sandstone columns of the ten-bay nave had the Early English pattern of shafts clustered on piers.

the site of Strata Marcella has been resurveyed by Clwyd-Powys Archaeological Trust and this has modified some of Stephen Williams' findings.