The remains of Betchworth Castle, a medieval fortified house with later alterations and additions. It is located on a sandstone spur which overlooks the western bank of the River Mole. The north eastern end, built of sandstone and brick, survives in a ruinous state to nine metres in height. The south western end survives only largely below ground.
Historical records indicate that Betchworth Castle dates to at least 1377, when Sir John Fitzalan, Marshal of England, was granted licence to crenellate his residence there. It is likely that the fortified house was constructed on the site of an earlier castle, traces of which may survive beneath the later buildings. The house subsequently underwent several phases of alteration and redevelopment, including a major remodelling during the mid 15th century.
The house and its park were bought in 1791 by William Fenwick, who arranged for the demolition of the south western end of the building, turning the remaining north eastern end into a smaller country residence. In 1798 John Soane was commissioned by the then owner, Henry Peters, to design alterations and new additions to the house and park. The house was bought by Henry Hope in 1834, who, because it formed only a peripheral part of his larger estate, allowed much of the reusable masonry to be removed from the house, the remainder of which gradually fell into a picturesque ruin.