ROTHESAY, a royal burgh, and the principal town of the county of Bute, Scotland, is situated in the island of Bute, at the head of a well-sheltered and spacious bay in the Firth of Clyde, 40 miles W. of Glasgow and 18 S.W. of Greenock, with which there is frequent communication by steamers. The bay affords good anchorage in any wind, and there are also a good harbour and pier. The town is the headquarters of an extensive fishing district, and is much frequented as a watering place. Besides two hydropathic establishments, it has several hotels and numerous lodging houses. Facing the bay there is an extensive esplanade. In the centre of the town are the ruins of the ancient castle, supposed by some to have been erected in 1098 by Magnus Barefoot, and by others at the same date by the Scots to defend themselves against the Norwegians. Tho village which grew up round the castle was made a royal burgh by Robert III., who created his eldest son David duke of Rothsay. During the Commonwealth the castle was garrisoned by Cromwell's troops. It was burned by the followers of Argyll in 1685, and remained neglected till the rubbish was cleared away by the marquis of Bute in 1816. The principal modern buildings are the aquarium, the town-hall and county buildings, the public halls, the academy, and the Thomson institute. The corporation consists of a provost, three bailies, a dean of guild, a treasurer, and twelve councillors. The population of the royal burgh in 1871 was 8027 and in 1881 it was 8291.