Simple in plan, the original castle was built by William de Eynsford and consisted of a stone structure, located within a bailey and enclosed by a curtain wall. Various 12 th century buildings were contained in the bailey, but the most important comprised the living accommodation, with a private solar, and a large hall situated on the first floor. Although this building was not designed with defence as a priority, the undercroft beneath served to raise the residential quarters above the level that could be subjected to a relatively easy attack. Today, only the massive walls of the undercroft remain. Large, craggy sections of the curtain wall have survived, some standing to a height of 30ft, and evidence of the latrines can be found along them.
Nothing remains of the castle gateway, and only fragments of the gatehouse exist.
The stone gate tower to the south of the building dates from the early 12 th century. Despite its largely ruinous state, Eynsford Castle holds an air of romanticism. Perhaps this is due to the idyllic, and unlikely, setting in the middle of a peaceful Kentish village, or maybe the undiscovered secrets held within its ancient walls give the site an enchanting atmosphere.