It was rebuilt in stone in the 12th century and then substantially redeveloped by Richard of Cornwall after 1227, including a high tower to enable visitors to view his surrounding lands.

[1] By 1842, the remaining prisoners had been moved to Bodmin Gaol and the site was closed, the castle being landscaped to form a park by the Duke of Northumberland.

[2] It was built at a strategic location, then called Dunheved, controlling the area between Bodmin Moor and Dartmoor, and the access over the Polson ford into Cornwall.

[13] Some of these houses may have belonged to the members of the castle-guard, feudal knights who were granted local estates in return for helping to defend the castle.

[20] Richard rebuilt the walls and the gatehouses at Launceston, building a high tower to increase the height of the keep, probably to allow guests to enjoy the view of his deer park.

[24] Richard built a stone wall around the new town, linking it to the castle defences, intending it both as a defensive measure and to impress visitors.

[31] Repairs to Launceston were undertaken in the 1340s and Edward held a council meeting at the castle in 1353, which was increasingly being used mainly for the holding of judicial assizes and as a gaol.

[32] In the 15th century, the castle's bailey was subdivided by a long wall, and the high tower on top of the keep was turned into an additional prison building.

[32] Launceston played little part in the dynastic Wars of the Roses that broke out after 1455; the castle was given to the Yorkist favourite Halnatheus Malyverer in 1484, but Henry VII's victory the following year saw him replaced by Sir Richard Edgcumbe.

In 1548, Sir William Body, a royal commissioner sent by Edward VI to destroy the Catholic shrines at Helston, was killed by two local Cornish men.

[38] John Russell, the Earl of Bedford, subsequently defeated the rebels and retook Launceston, capturing Arundel who was seized in the street fighting.

[39] During the 16th century, the castle began to be used as a rubbish tip by the adjacent town, and under Henry VIII the deer park, which was no longer needed to generate venison for the duchy, fell into disuse.

[43] Before retreating from the town, the Royalist forces reportedly stripped the castle of the lead from its roofs and gave the timbers to the townsfolk to use as fuel.

[44] In the same year, Parliament sold off the properties of the duchy of Cornwall, and Colonel Robert Bennett, a Baptist teacher and supporter of Oliver Cromwell, purchased the castle, its deer park and its gaol.

[45] The north gatehouse began to be partially used as a prison, and in 1656 was used to hold various members of the Society of Friends, including George Fox, their founder, who described it as a "nasty stinking place".

[50] In 1690, the county complained to the King that the constable, Sir Hugh Pyper, had allowed it to fall into disrepair and that the male and female prisoners were sleeping together in the same quarters.

[52][c] The Pyper family's control of the constableship concluded in 1754, and George II then appointed a sequence of constables who became responsible for running the castle and county gaol on behalf of the duchy of Cornwall.

[61] This required the demolition of part of the castle wall and the fortified bridge, and the weakening of the foundations caused the subsequent collapse of the south-eastern tower later that year.

[62] In 1838 the county government and the assizes were moved to Bodmin, which was more centrally located in Cornwall, resulting in the closure of the castle's gaol and its final demolition in 1842.

[63] By now the castle was in disrepair, and the bailey and the earthworks were covered with a combination of pigsties, cabbage gardens and a skittle alley used by a local pub.

[66] Hugh sold off his local interests in 1864 and the Northumberlands' control of the post of constable lapsed with the death of his brother Algernon Percy, the 4th duke, the following year.

[67] The post lay vacant until in 1883 the local Member of Parliament, Hardinge Giffard, was appointed as the constable by the then Prince Edward in his capacity as the Duke of Cornwall.

[67] During the later stages of the Second World War, the bailey was levelled and used to hold a set of temporary Nissen huts that formed a hospital for United States Army personnel.

[70] In the 21st century, Launceston Castle is owned by the duchy of Cornwall and operated by English Heritage; as of 2013, annual visitor numbers averaged between 23,000 and 25,000.

[77] The south gatehouse has two drum towers on either side of a gateway, protected by a portcullis, and would have had three floors, linked to a wall walk around the castle.

[82] Much of the wall, including the south-eastern tower–called the Watch or Witch Tower–has been destroyed, although around a stretch 50 metres (160 ft) long survives on the south-west side.

[90] Visitors would have been funnelled around the edge of the park and by the town wall towards the south gate of the castle, a route dominated by the views of the keep and tower.