Eynsford Castle is one of the earliest examples of a stone enclosure castle in England. It started out as a raised area of ground with a wooden tower upon it, next to the River Darent. In about 1088 the raised earth platform was surrounded by a 6 metre (20ft) tall wall made of coursed flint rubble. Several decades later the height of the wall was increased to 9.1 metres (30ft) and a new stone hall and a stone gate tower were built. After a fire in 1250 the hall was rebuilt and extended by William de Eynsford, creating a larger more comfortable manor house. The ruins of this house and some quite substantial sections of wall still remain.