Stratford Langthorne Abbey, or the Abbey of St Mary's, Stratford Langthorne was a Cistercian monastery founded in 1135 at Stratford Langthorne — then Essex but now Stratford in the London Borough of Newham. The Abbey, also known as West Ham Abbey due to its location in the parish of West Ham, was one of the largest Cistercian abbeys in England, possessing 1,500 acres (6.07 km2) of local land, controlling over 20 manors throughout Essex. The head of the community was known as the Abbot of West Ham.