Before the Norman Conquest there were no masonry built castles in Cornwall, only stockades of wood surmounting earthworks or piled up masses of stone uncemented. The usual Saxon Burh was a mound, surmounted by a structure of timber, reached by a bridge or ladder from a base-court that was encompassed by moat and mound and stockade. The Norman system of building a castle was to erect a round or square keep, a massive structure of stone, on the mound that had formerly been surmounted by a wooden structure, and to surround the base-court with a stone wall. Within this were erected the necessary domestic buildings. Very generally the entrance to the court was strongly defended by a second tower. The style of castle was greatly altered in the reign of Edward I but of such Edwardian castles there are no examples in Cornwall, save the poor fragment of Tintagel. The Normans built a castle at Launceston, and there the circular keep standing on a lofty tump of rock, artificially shaped, is of their construction, but the ruined buildings below, with the gateways and walls of the base-court, are later.

The castle of Trematon also consists of a "motte" surmounted by a circular keep, and a base-court with square tower at the entrance, with an archway.

Tintagel Castle is reduced to a miserable ruin, part on the mainland, part on the islet, with the intervening portion blocked up by fallen rocks, forming a narrow isthmus. The deep chasm that formerly separated the two portions of the castle was anciently spanned by a drawbridge. The work appears to be of the thirteenth century. On the island are the remains of a chapel with its altar slab still in place. Tintagel became a residence of the Earls of Cornwall, and in 1245, Richard son of King John received in it his nephew David, Prince of Wales. It was subsequently used occasionally as a prison. In the reign of Elizabeth, that penurious queen, deeming the expense of keeping it up too onerous, allowed it to fall into ruin.

St Michael's Mount was crowned with a castle and a church. The oldest portion is the central tower, of the fourteenth or fifteenth century; other portions are later additions, and much very bad modern work has tended to its sad disfigurement. Edward the Confessor planted a monastery on the rock, and granted it to Mont S. Michel in Normandy; at the Conquest it was made over to Robert Earl of Mortain, but the Benedictines of Mont S. Michel continued to have a cell there with a prior. It was consequently at once a religious house and a military post.

Restormel, near Lostwithiel, consists of a keep crowning a hill, with a gatehouse on the west, a projecting tower on the E.N.E., and a chapel. It is not older than the reign of Henry III and was the stronghold of the Cardinhams and then of the Traceys, from whom it passed to the Earls of Cornwall. The circular keep is only 30 ft. high. The castle was already ruinous in the time of the Civil War, but it was put in repair and held by the Parliamentary forces till taken by Grenville.

St Mawes is a small but perfect castle, erected by Henry VIII.

St Mawes Castle

St Mawes Castle

Pendennis Castle was another erection of Henry VIII, on the site of earlier fortifications. The circular tower dates from his time, but it was added to considerably in the reign of Elizabeth. In 1644 Pendennis afforded shelter to Queen Henrietta Maria, when embarking for France, and hither came Prince Charles in 1646 on his way to Scilly.

Helsborough, near Michaelstow, was a fortress belonging to the Earls of Cornwall, but it shows no tokens of having ever been walled with masonry. The only structural remains to be seen are the ruins in the midst of a Perpendicular chapel.

On Carn Brea is a tower, another on Roche rock; and St Catherine's Castle, erected by order of Henry VIII, defended the entrance to the harbour of Fowey.