The site of Leiston Abbey comprises the standing and buried remains of a monastic church and conventual buildings, together with adjacent earthworks and water control features, and a moated site. It was founded in 1182 on a site nearby, but moved here sometime after 1363 as the original location was prone to flooding. In 1380 or 1389 the new buildings, with the exception of the church, were extensively damaged by fire.
The abbey buildings were constructed of flint rubble and mortar, but also contain local mudstone, reused limestone and brick. The remains of the church lie north of the claustral range. Today, the north chapel at the east end of the church is still in use. In the post-medieval period the outer walls of the south aisle and the eastern part of the north aisle were incorporated into buildings. In the 17th century, Abbey House was built on to the south aisle wall and later extended in the 19th and 20th centuries.
The main entry to the cloister is a passage through the west range, fronted by a porch dated to the late 15th or early 16th century. This west range probably contained the abbot's apartments and perhaps guest accommodation as well as an undercroft. The south range is the best preserved of the three. It includes the remains of an undercroft, refectory, monastic kitchen and washing place. The undercroft was altered in the late 14th century. The east range comprised the dormitory, chapter house, a possible sacristy, the warming house and latrine.
To the east and north east are the buried remains of a possible infirmary and gatehouse as well as a ditch. To the north west are two buildings which are partly of monastic date surrounded on three sides by a ditch considered to be a moat, possibly predating the construction of the abbey. There are also two ponds thought to either be part of another moat or monastic fish ponds.
The abbey was suppressed in by Henry VIII 1536 and in 1537 was granted to Charles Brandon, Duke of Suffolk.