At the time of the Norman Conquest in 1066, Plymouth, then known as Sutton, was too small a settlement to warrant fortification, but a motte and bailey castle was built at nearby Plympton.
The exact date of the construction of the castle itself is uncertain, but following a French raid on Plymouth in August 1403, King Henry IV ordered the prior of Plympton and the abbot of Tavistock to further fortify the town with walls and towers.
[3] In 1542, the antiquary John Leland visited Plymouth and recorded that: "On a rokky hill hard by it [the mouth of the harbour] is a strong castel quadrate having a eche corner a great rounde tower.
During the English Civil War, Plymouth declared for Parliament and was besieged in 1643 by Royalist forces; the castle was again made ready for defence but saw no action.
[1] A small section of the castle fabric survives in the Barbican area of Plymouth, located in Lambhay Street, at the head of a flight of stairs leading down to the Mayflower Steps on the quayside.