Kilchurn castle is situated on a peninsula at the north end of Loch Awe, and is well protected by water and marsh, while the buildings stand on a rocky platform of irregular shape, but with perpendicular faces, about 15 feet high, on three of its sides.
The plan of this keep has some peculiarities. The entrance door is in the north-east wall on the ground floor, and the stair to the upper floors starts from the opposite corner of that floor. The stair is unusually easy, being a square stair, so arranged that small vaulted rooms are provided on each side of it at the east end of the keep. The exterior is of the usual plain style and is built with granite rubble-work. The corbels carrying the corner bartizans are all cut out of the hardest gneiss or granite.
The additions were built in 1693, this date being carved on the work in two places, viz., the entrance door and the door to the stair turret on the south side of the keep. The first of these inscriptions is rather remarkable, and might be misleading. The original lintel of the entrance door of the keep has been removed, and a new lintel inserted, bearing the date 1693, and the initials and arms of John, first Earl of Breadalbane, and of his second wife, Countess Mary Stewart1 or Campbell.
Another curious circumstance connected with this door is, that it is the only entrance to the castle, so that to get into the quadrangle one has to pass through the narrow entrance door and cross the ground floor of the keep.
The additions made in 1693 convert this keep into a castle surrounding an irregular quadrangle.
The additional buildings have been very extensive, and would accommodate a large garrison, but they are not built with a view to resist a siege. The round towers at the angles and the numerous square loopholes on the ground floor would, however, suffice to defend the garrison against a sudden attack by Highlanders, which was probably what was to be chiefly apprehended in that inaccessible situation. Although this castle presents a striking and imposing appearance at a distance, it is somewhat disappointing on closer inspection. The interior walls are much destroyed, and the internal arrangements of the plan can scarcely be made out. The buildings have more the appearance of modern barracks than of an old castle. There are two kitchen fireplaces, and probably there were officers’ quarters and men’s quarters, while the keep and some additional accommodation adjoining would be set apart for the lord and his family.
— David MacGibbon and Thomas Ross, Castellated and Domestic Architecture of Scotland, 1887.
1 The identification with Stewart would appear to be an error. Lady Mary Campbell was born after 1634. She was the daughter of Archibald Campbell, 1st Marquess of Argyll and Lady Margaret Douglas. She married, firstly, George Sinclair, 6th Earl of Caithness, son of John Sinclair, Master of Berriedale and Lady Jean Mackenzie, on 22 September 1657 at Roseneath, Dunbartonshire, Scotland. She married, secondly, John Campbell of Glenorchy, 1st Earl of Breadalbane and Holland, son of Sir John Campbell of Glenorchy, 4th Bt.and Lady Mary Graham, on 7 April 1678. She died on 4 February 1690/91.