A Cistercian Abbey was founded at Hazleton in the 12th century by the monks of Kingswood (ST 79 SW 12). They later went back to Kingswood circa 1150, but some returned to Hazleton before moving to a more suitable site at Tetbury circa 1150 (ST 89 SE 15). Hazleton continued as a grange of Tetbury up to the Dissolution. Hazleton Manor (16/17th century with 20th century additions and alterations) occupies the site.
A barn, "Abbey Barn", built by Abbot Henry in AD 1290 (as recorded on a stone, now lost) is all that survives. It was so severely damaged in a fire of 1885 that it is difficult to distinguish original remains from subsequent repairs.
The original remains of the 13th century stone-built Abbey Barn comprise the east wall to a height of 2.5m together with the North-East corner and the south end wall to a height of 5.0m, together with the South-West corner. Most of the west wall and north end wall are gone, and a parapet tops the remaining walling which has been reconstructed in the 19th century to a height of about 5.5m.