The monument includes Castle Mound, a motte castle situated on high ground which slopes westwards to Cambridge Brook. The motte survives as an earthwork c.10m high and 61m in diameter surrounded by a ditch c.3.5m deep and between 10m and 12m in width. The ditch is dry except for a small area on the western side which is water filled. Also on the western side of the motte is a depression 1m by 0.5m deep which was probably caused by an unrecorded excavation. A bailey associated with the motte was once situated to the south and was traceable in 1960 along the western fence line of the graveyard. It is, however, no longer visible at ground level, having been overlain by development and is not included in the scheduling, although remains are believed to survive in the area of the churchyard. To the south west of the motte, also outside the scheduling, is a rectangular-shaped area of earthworks which is considered to be the remains of a terraced garden for the Hall. The castle is believed to have been owned by the Sackvilles and built during the reign of either King Stephen or Henry I. <1>