Dramatically situated beside Loch Sween

on a rocky outcrop where the long, narrow loch begins to open out into the sea, Castle Sween is one of the oldest stone castles in Scotland. The most ancient part, built some 800 years ago by Suibhne, the ancestor of the Mac-Sweens, is a rectangular enclosure with heavily buttressed walls, thick enough to support the wall-walk from which the castle would have been defended.
Inside the enclosure, traces of stone buildings can still be seen, as well as slots in the walls where timbers would have supported floors and roofs. A modest extension was built on the seaward side soon after the construction of the first part, and at the beginning of the 14th century Sir John Menteith, then lord of Knapdale, extended this wing to form a three-storeyed tower, with a massive circular garderobe tower to the north.

The castle was completed, probably in the 16th century, by the addition of a further tower on the northeast corner, with a large kitchen on the ground floor and a chamber above. Throughout the building the external windows are very small, giving the castle a grim and for-
bidding look.  In the latter part of the 15th century Knapdale came within the lordship of the Isles, and the MacNeills of Gigha were appointed keepers of the castle.  Hector MacNeill, who was keeper until 1472, was succeeded by his son-in-law Alexander MacMillan, who commissioned the MacMillan Cross at Kilmory Knap, further down Loch Sween.

However, in 1475 John MacDonald, lord of the Isles, forfeited Knapdale to James III; and in 1481 the king granted it to Colin Campbell, first earl of Argyll. The castle remained a Campbell stronghold until 1645, when it was taken by the Royalist forces of Colkitto, Alexander MacDonald, and burned. Castle Sween lay derelict for nearly three hundred years until 1933. A thorough overhaul of the masonry was finally undertaken. In addition, a stairway has been built to give access to the garderobe tower. Grim stronghold though it now appears, Castle Sween would seem to have been the centre of a flourishing community in the 14th and 15th centuries. The grave-slabs and crosses at Kilmory Knap are evidence that this community included a group of sophisticated craftsmen closely related to the gentry, and it is probable that the dark interiors of the castle were furnished richly by the standards of the time. Today the rough bare walls are witness to the violence of past conflicts in the western Highlands, the memory of which still draws visitors to this singularly beautiful part of Argyll.