It has an irregular layout with four rectangular turrets round a core of the same height and an embattled parapet.

[3] Antiquarian William Worcester recorded that there were 32 castles on the Cornish peninsula, including Carn Brea which was described as a tower.

[4] The castle was extensively rebuilt in later periods, primarily in the 18th century by the Basset family as a hunting lodge.

[5] It is considered a folly, due to the huge uncut boulders that make up part of its foundations, giving the impression of the building melting into the land.

[6] Its use as a beacon for ships was recorded in 1898 when stipulated in the lease, the tenant agreeing to show a light in the north facing window.