Barnes Castle is interesting for two main reasons – it is built on an unusual axial plan, and it was never finished.

Sir John Seton of Barnes, a diplomat at Philip II of Spain’s court and later James VI’s Treasurer of the Household and a Lord of Session, began building Barnes Castle in the late 16th century, but his death in 1594 put an end to the building work, and the castle was never completed.

Sir John owned the nearby Garleton Castle, and was probably responsible for rebuilding it around an earlier core. But it may be that he wanted to build himself something more modern, hence the unusual design of Barnes.

Barnes Castle is built on a north-east to south-west axis, and overall is rectangular in shape, measuring 50m by 39m. At each corner is a large square tower, and on the walls between them are smaller towers – two on the north-west, one on the south-east, and one forming the entrance gate on the south-west wall.

Each of the corner towers has gun loops pointing along the walls towards the next tower, allowing the castle’s defenders to shoot at attackers even when they were close to the castle. Interestingly there are also gun loops pointing in towards the internal courtyard, possibly to allow a defence to continue even if the outer walls had been breached.

The ground floor of the castle is vaulted, and the walls, which are rubble-built and around 0.8m thick, only reach a maximum height of 4.3m. There are numerous large window openings in the walls which would render the castle rather weak, unless they were added later.

Barnes Castle is now used as a farm store for nearby Barney Mains.