The monument includes an enclosure castle situated on the east bank of the River Darent, the valley of which cuts through an area of gently undulating chalk downland. The castle has an inner ward constructed on a low oval platform, enclosed by a curtain wall with a moat to the north, east and south. The central platform on which the castle buildings were constructed is c.2m above the surrounding ground level and measures 61m north-south and 40m east-west. The curtain wall survives as upstanding masonry c.8.8m high, constructed of coursed flintwork c.1.8m thick at the base. The north west segment has collapsed but remains where it fell. Within the ward are the ruined remains and buried foundations of a 12thcentury hall block, the undercrofts of which still survive. This was a freestanding building, 22m east-west by 13m north-south, in the northern half of the ward and was mainly constructed from reused Roman tile probably brought from Lullingstone or Farningham. A stair and porch were built on the south side of the building and a later kitchen was constructed between the hall and the curtain wall to the north. The 12th-century kitchen was located in the west corner of the ward and a gate-tower was situated on the south east side at the main entrance to the castle. To the north, east and south of the curtain wall lies the moat which, although having become partially infilled over the years, is visible as an earthwork feature up to 16m wide and 1.5m deep. To the west the castle was protected by the river. Access to the castle was gained by way of a bridge leading across the moat in the south east to the gate-tower. The curtain wall is believed to have been constructed c.1090 by William de Eynsford, possibly on the site of an earlier earthwork castle with a timber watch-tower. Although such a site is not mentioned in the Domesday Book, traces of a central wooden building, contemporary with the early phase of the curtain wall, have been discovered during excavations. The hall, gate-tower and heightened curtain wall are ascribed to William II in c.1130, with the reconstructed hall and new kitchens dating to c.1230. Documentary evidence records a complaint about the doors and windows of the castle having been broken down, damage committed and stock let loose. This resulted in the dismantling of the structures inside the curtain wall in or just before 1312. Partial excavation took place in 1835 and further excavations were carried out between 1953 and 1971 during the conservation of the monument. These revealed the internal structure and accommodation areas within the curtain wall as well as confirming the 14th-century destruction of the castle. Excluded from the scheduling are the modern buildings, works sheds, rubbish bins, wooden benches, paving, wooden bridge and fencing, although the ground beneath all these features is included.