Castle Hill, Brighton

Castle Hill is a Site of Special Scientific Interest near Brighton, England. To the north-west this SSSI is in the parish of Kingston near Lewes; the rest is in the city of Brighton and Hove, a Unitary authority, while the whole of the SSSI and most of its surrounding farmland is owned by Brighton and Hove City. English Nature classify it under East Sussex. The site is within the South Downs AONB (Area of Outstanding Natural Beauty) and the northern part of the site is a national nature reserve.

The site is listed as of biological interest due to its chalk grassland habitat supporting a variety of flora and fauna.

Just inside the most north-western corner of the reserve, near the summit of Newmarket Hill, is the site of a nineteenth-century farm labourer's cottage and barns, known as Newmarket Farm. It is now an overgrown pile of demolition rubble, having been used for artillery practice during the Second World War by Britain's allies. To the south, the SSSI surrounds the former hamlet of Balsdean which was also demolished as a result of the same Second World War artillery.