The Abbey of St Mary is a ruined Benedictine abbey in York, England and a Grade I listed building.
Once the richest abbey in the north of England, it lies in what are now the York Museum Gardens, on a steeply-sloping site to the west of York Minster.
The original church on the site was founded in 1055 and dedicated to Saint Olaf II of Norway. After the Norman Conquest the church came into the possession of the Anglo-Breton magnate Alan Rufus who granted the lands to Abbot Stephen and a group of monks from Whitby. The abbey church was refounded in 1088 when the King, William Rufus, visited York in January or February of that year and gave the monks additional lands. The following year he laid the foundation stone of the new Norman church and the site was rededicated to the Virgin Mary. The foundation ceremony was attended by bishop Odo of Bayeux and Archbishop Thomas of Bayeux. The monks moved to York from a site at Lastingham in Ryedale in the 1080s and are recorded there in Domesday. Following a dispute and riot in 1132, a party of reform-minded monks left to establish the Cistercian monastery of Fountains Abbey. In 1137 the abbey was badly damaged by a great fire. The surviving ruins date from a rebuilding programme begun in 1271 and finished by 1294.