Comlongon Castle is a tower house dating from the 15th century. It is located 1 km west of the village of Clarencefield, 10 km south-east of Dumfries, in south west Scotland. The original tower was extended by the addition of a 19th-century baronial style mansion. The castle and mansion are now a hotel.
Thomas Randolph, 1st Earl of Moray granted the lands of Comlongon, in the early 14th century, to his nephew William de Moravia, ancestor of the Murrays of Cockpool. His descendant Cuthbert of Cockpool (d.1493) built Comlongon Castle in the later part of the 15th century, to replace the Murrays' earlier castle of Cockpool, of which only earthworks remain at Cockpool Farm, to the south west of Comlongon. His son John Murray (d. c.1527) was created Baron Cockpool in 1508. Descendants of the Murrays were later created Viscounts Stormont in 1621, and Earls of Mansfield in 1776, and Comlongon was part of the Earl's estate until 1984. The castle is reportedly haunted by the ghost of Lady Marion Carruthers who took her own life by leaping from the lookout tower.
The red sandstone tower is approximately 15m by 13m, and 18m high to the corbelled parapet. It was built on a stone 'plinth', in order to support the structure on what was a marshy site. The entrance to the tower still retains the original yett, a portcullis-like metal grid in front of the door. This leads into a vaulted cellar with a well, and two spiral stairs leading up. The main stair at the north-east corner leads up to a caphouse at parapet level, while the second serves the high-table end of the first floor hall.
The hall is dominated by a large fireplace, with the Royal Arms of Scotland carved above it. Heraldic emblems are carved onto several projecting corbels, and an elaborately decorated recess or aumbry, with a carved cinquefoil surround, attests to the relative wealth of the Murrays. A separate fireplace at the opposite end of the hall would have served the narrow kitchen, and would have been separated from the hall by a timber screen where a wall now stands.