Over the centuries, several other structures were added, with medieval monarchs investing heavily in what was then an important fortress that guarded the Yorkshire coastline, Scarborough's port trade, and the north of England from Scottish or continental invasion.

[2][3][4] Among finds dating back about 3,000 years, a Bronze Age sword, thought to have been a ritual offering, is on display in the castle exhibition.

[6] A much later Icelandic poem[8] claims that a Viking settlement around the harbour was burnt down in 1066 by Hardrada's forces, who built a large bonfire on the headland to supply burning brands to hurl at the villagers below.

Initially, Aumale resisted the call to hand over Scarborough, which he had built on a royal manor, until Henry's forces arrived at York.

The wooden castle vanished – William of Newburgh, writing near the time, claimed that the structure had decayed through age and the elements, battered beyond repair on the windswept headland.

[17] Later interpretations view this as implausible and argue that Henry wanted to stamp his mark on Scarborough, by demolishing William's fort and creating a much stronger stone complex.

Much of the building work occurred between 1159 and 1169, when the three-storey keep was built and a stone wall replaced the wooden palisade protecting the inner bailey.

[26] The Pipe Rolls, records of royal expenditure, show that John spent over £17,000 on 95 castles during his reign spread, and Scarborough received the most investment.

[31] By the mid-to-late 13th century, the defences were decaying, floorboards rotted, roof tiles were missing and armouries bare of weaponry.

[37] The castle was considered to be the natural place for the king's favourite knight, the Gascon Piers Gaveston, to seek sanctuary when pursued by the barons who had imposed the Ordinances of 1311.

Scarborough fared little better; Edward punished the town for not supporting Gaveston by revoking its royal privileges and placing it under the direct rule of appointed governors.

[35] After assaults by forces from France and Scotland in the early 16th century, in 1536 Robert Aske unsuccessfully tried to take the castle during the Pilgrimage of Grace, a revolt against the Dissolution of the Monasteries and Henry VIII's (reigned 1509–1547) break with the Roman Catholic Church.

[34] In 1557, forces loyal to Thomas Wyatt the younger, who opposed Mary I (reigned 1553–1558) and Catholicism, took the castle by entering disguised as peasants.

Their leader, Thomas Stafford, held the castle for three days, and was subsequently executed for high treason on Tower Hill.

[30][42] In September 1642, at the outbreak of the English Civil War (1642–1651), Sir Hugh Cholmley occupied the castle as a Parliamentarian loyal to Oliver Cromwell but swapped sides in March 1643.

[43] After Cholmeley's defection, the castle, with its garrison of 700 Royalist soldiers, the town and its strategic supply port were on the side of Charles I.

[44] On 18 February 1645, Sir John Meldrum took the town from the Royalists, cutting off any escape routes by land or sea and delivering the port for Parliament.

[34] The same day, Cholmley retreated into the castle and refused to give in, so the Parliamentarians prepared for what would be a five-month siege – one of the most bloody of the Civil War, with almost continuous fighting.

The Parliamentary forces were unable to take the castle and there followed a period of particularly bloody hand-to-hand fighting around the barbican gateway in which Sir John Meldrum was killed.

[34][53] The castle was later used as a prison for those who were deemed to be enemies of the Commonwealth of England, the country's brief period of republicanism; the shell of the keep survives, minus the west wall, which was destroyed in the bombardment.

[54] The Jacobite Rebellion of 1745, a series of uprising aimed at restoring the Catholic House of Stuart to the throne, saw the castle refortified with gun batteries and barracks for 120 officers and men by 1746.

In 1748, the Master Gunner's house was constructed and served as accommodation until the early 20th century and today hosts the exhibition on the castle.

[56] The castle's location takes advantage of a naturally defensive site on a headland with steep cliffs, 300 feet (91 m) high, on three seaward sides.

The promontory is joined to the mainland by an isthmus, where a ditch or moat was cut, and a wall or palisade with a gatehouse built on the southwest landward side.

The stone curtain wall dates from the late 12th and early 13th centuries when it was strengthened by the addition of twelve round towers at intervals on its 230 yards (210 m) length.

The entrance consists of a barbican, or fortifications to protect the gateway, completed in the 14th century and flanked by two half-circular towers on high ground.

[34][62] In the outer bailey, a building named the "King's Chambers" or Mosdale Hall, after a 14th-century governor responsible for upgrading it, is an example of how the castle has been altered over the years.

The 13th-century Queen's Tower, in the wall nearby, also had different uses: initially luxurious accommodation with private latrines, a porch and large windows with bay views were added in 1320.

His nephew, Ted Temple shares his story of being the last resident of The Master Gunner's House in the Scarborough Review of June 2017, page 12.

The castle site, a scheduled ancient monument managed by English Heritage since 1984,[36] is host to various events, usually in summertime, such as pirate and Robin Hood-themed activities[65] and an annual Kite Festival.