Castle Rushen () 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 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. Make-up of the castle The keep of Castle Rushen's first line of defence is an outer wall, high and thick. Attached to the wall are five towers, which in the post-defensive era of Castle Rushen were used for civilian administrative functions. The keep itself has walls thick at the base and thick at the top. Four towers sit atop the keep, the main one in the north rising to a height of and other three to around . The entrance to the keep is protected by a drawbridge and a fortified inner gatehouse entrance with two portcullises with a killing area between them covered by three so-called murder holes, through which the defenders could attack any intruders trapped between the two portcullises. On either side of the gatehouse are located guardhouses, which were converted into prison cells in the later history of the castle. When on duty, the garrison would spend most of its time in the gatehouses. Inside the gatehouse is a lower level with a tide mill for grinding corn. The castle also included a medieval chapel, housing Castle Rushen's