Castle Rushen (Manx: Cashtal Rosien) is a medieval castle located in the Isle of Man's historic capital, Castletown, in the south of the Island. It towers over the Market Square to the south-east and the harbour to the north-east. The castle is amongst the best examples of medieval castles in Europe and is still in use as a museum and educational centre. Construction is thought to have taken place during the 10th-century reigns of rulers of the Isle of Man – the Kings of Mann and the Isles. An old oak beam was found in the castle in the mid-19th century that contained the date 947. The last such King of Man, Magnús Óláfsson, is recorded in the Chronicle of Mann to have died at the castle in 1265. The original Castle Rushen consisted of a central square stone tower, or keep. The site was fortified to guard the entrance to the Silver Burn. The castle was developed by successive rulers of Man between the 13th and 16th centuries. The limestone walls dominated much of the surrounding landscape, serving as a point of dominance for various rulers of the Isle of Man. By 1313, the original keep was reinforced with towers to the west and south. In the 14th century, an east tower, gatehouses, and curtain wall were added. After its initial construction and use by the Norse-Gaelic rulers of the Isle of Man, the castle changed hands repeatedly between the Scots and the English. The Isle of Man was transferred to Scotland the year after Magnús Óláfsson's death as part of the Treaty of Perth, ending the 1263–1266 Scottish–Norwegian War. On 18 May 1313, with the help of his friend, Angus Og Macdonald, Lord of the isles and his fleet, the Scottish king Robert the Bruce invaded the Isle of Man at Ramsey. The Island was captured in five days, the only resistance occurring at Castle Rushen, which was defended by Dungal MacDouall, who had once been Lord of Galloway and betrayed Robert Bruce's brothers, Alexander and Thomas, to Edward I who promptly had them executed as traitors. After a three-week siege, Robert captured the castle on 12 June 1313, gaining the Isle of Man as an outpost securing the approaches to western Scotland and the Hebrides. After several more changes of hands the English and their supporters eventually prevailed. The English king Edward I Longshanks claimed that the Island had belonged to the Kings of England for generations and he was merely reasserting their rightful claim to the Isle of Man. From 1405 to 1738 the Isle of Man was controlled by the Stanley family, beginning with Sir John Stanley, who was given the title of King of Mann by Henry IV of England in 1405. The title King of Mann was replaced in 1521 by the title Lord of Mann, held today by the reigning British monarch.