Castle Rushen in Castletown is one of Europe's best-preserved medieval castles, with origins likely in the 10th-11th centuries under the Kings of Mann and the Isles; an oak beam dated to 947 was found in its walls during 19th-century repairs. It was besieged and captured by Robert the Bruce in 1313 after a three-week siege, bringing the island briefly under Scottish control. From 1405 to 1738 the Stanley family (Lords of Mann) governed the island from the castle, which also served as an administrative centre, mint, and law court. Its defensive role declined through the 18th century and it was later used as the Isle of Man's prison until 1891. Restored by Manx National Heritage, it reopened as a heritage museum in 1991 and remains a dominant landmark of Castletown, the island's former capital.