Rothesay Castle Rothesay Castle is a ruined castle in Rothesay , the principal town on the Isle of Bute , in western Scotland . Located at , the castle has been described as " one of the most remarkable in Scotland " , for its long history dating back to the beginning of the 13th century , and its unusual circular plan . The castle comprises a huge curtain wall , strengthened by four round towers , together with a 16th - century forework , the whole surrounded by a broad moat . Built by the Stewart family , it survived Norse attacks to become a royal residence . Though falling into ruin after the 17th century , the castle was repaired by the Marquess of Bute before passing into state care in the 20th century . The early castle . The castle was built either by Alan , High Steward of Scotland ( d . 1204 ) , or by his son Walter Stewart ( d . 1246 ) . Alan was granted the lands of the Isle of Bute by William I in 1200 . A wooden castle was constructed first , but the stone circular curtain wall was in place by the 1230s , when the castle was attacked and taken by Norsemen under Uspak , possibly a grandson of Somerled . According to " The Saga of Haakon Haakonsson " , the Norsemen fought for three days to take the castle , breaking down part of the eastern wall by hewing the stone with their axes . This saga is the earliest recorded account of an assault on a Scottish castle . In 1263 , Rothesay was taken again by the Norse under Haakon IV before the Battle of Largs . Although the Battle of Largs was indecisive , Haakon ' s campaign was unsuccessful , and effectively ended Norse influence in western Scotland . The early castle comprised only the roughly circular curtain wall , 3m thick and around 43m across , built on a low mound , with a battlement on top accessed by open stairs . The moat was connected to the sea , the shoreline then being closer to the north - east of the Castle than it is today . The broad crenellation s can be made out within the walls , which were later raised . Holes in the upper wall would have supported a timber bretasche , a projecting structure serving as an extended battlement . This curtain wall was built of coursed ashlar , and had only two openings in its length . The main gate was an arched opening with a simple timber door . The second opening was a small postern gate in the west wall , later blocked . In the later part of the 13th century , the castle was strengthened by the addition of four round towers , of which only the north - west survives intact . These three - storey towers had strong splayed bases , with arrow slits below the crenellated parapet . A portcullis was added to the main gate . Wars of independence and the rise of the Stewarts . During the Wars of Scottish Independence , Rothesay was held by the English , but was taken by Robert the Bruce in 1311 . It then returned to English hands in 1334 , before being taken again by the Scots . Following the accession of the Stewarts to the throne of Scotland in 1371 , the castle became a favourite residence of kings Robert II and Robert III , who died here in 1406 . Robert II granted the hereditary keepership of the castle to his son John , ancestor of the Earls and Marquesses of Bute . Robert III made his eldest son David Duke of Rothesay in 1401 , beginning a tradition of honouring the heir to the throne of Scotland with this title . In 1462 the castle survived a siege by the forces of John of Islay , Earl of Ross and the last Lord of the Isles . 16th and 17th centuries . In the early 16th century Rothesay Castle was strengthened again . Construction of a gatehouse keep , extending from the north of the curtain wall , began around the turn of the century , to provide more modern accommodation for James IV . The curtain wall itself was raised up to ten metres in height , the works continuing into the reign of James V . In 1527 the castle withstood another siege by the Master of Ruthven , which destroyed much of the burgh of Rothesay . In 1544 , the castle fell to the Earl of Lennox , acting for the English during the so - called " Rough Wooing " . The forework is an L - plan structure , which jutted into the moat and was accessed by a drawbridge . The lower floor comprised a vaulted entrance tunnel running into the older castle courtyard . Above , the four storey tower contained royal lodgings , and still bears the royal coat of arms above the door . Also in the early 16th century , a chapel was constructed inside the old castle . Simple in form , the chapel measured around 6m by 9m , and is now the only surviving structure within the curtain wall . The north - west tower was converted into a doocot , and is known as the " Pigeon Tower " , due to the nest boxes built into the outside wall . Rothesay was garrisoned for the Royalists during the Wars of the Three Kingdoms , then for the occupying forces of Oliver Cromwell , who invaded Scotland with his New Model Army in the early 1650s . On their departure in 1660 , the troops partially dismantled the structure . What was left was burned by the supporters of Archibald Campbell , 9th Earl of Argyll during his rising of 1685 , in support of the Monmouth Rebellion against James VII . Repair and restoration . Following a long period of neglect , the 2nd Marquess of Bute employed 70 men to excavate the ruins , clearing large amounts of rubbish from the castle in 1816 - 17 . But it was not until the 1870s that the ruins were stabilised . The 3rd Marquess , a keen restorer of historic buildings , embarked upon a series of repairs and restorations , following surveys and advice from his regular architect William Burges . His " restorations " continued until 1900 , and include the clearing and shaping of the moat , as well as the red sandstone additions to the forework , which reinstated the hall roof while significantly altering the character of the building . In 1961 Rothesay Castle was gifted to the state , and is now a Scheduled Ancient Monument , in the care of Historic Scotland . The castle is open to visitors year round . Fine views can be seen from the top of the walls over the town and back towards the mainland .