Castle Hill is a Site of Special Scientific Interest

Site of Special Scientific Interest

A Site of Special Scientific Interest is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon...

 in Brighton

Brighton

Brighton is the major part of the city of Brighton and Hove in East Sussex, England on the south coast of Great Britain...

, England. Although Brighton is a Unitary authority

Unitary authority

A unitary authority is a type of local authority that has a single tier and is responsible for all local government functions within its area or performs additional functions which elsewhere in the relevant country are usually performed by national government or a higher level of sub-national...

, English Nature

English Nature

English Nature was the United Kingdom government agency that promoted the conservation of wildlife, geology and wild places throughout England between 1990 and 2006...

 classify it under East Sussex

East Sussex

East Sussex is a county in South East England. It is bordered by the counties of Kent, Surrey and West Sussex, and to the south by the English Channel.-History:...

. The site is within the South Downs AONB (Area of Outstanding Natural Beauty) and 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.