Situated a mile (1.5 km) southeast of the village of Kilchoan on the Ardnamurchan peninsula, Mingary Castle occupies a dramatic location on a promontory overlooking the entrance to Loch Sunart and the island of Mull. Today a substantial ruin remains of a castle begun in the 13th century. Its outer wall takes the form of an irregular hexagon, is up to 2.7m (9 feet) thick and was once up to 12m (39 feet) high. The walls are thickest on the seaward side, which also provided the main entrance; the landward side was additionally defended by a rock-cut ditch some 7.5m (24 feet) wide which was once spanned by a drawbridge providing a second entrance. Most of the castle dates from a succession of building works between the 16th and 18th centuries.
The castle was the seat of the MacIans of Ardnamurchan, a sept of the MacDonalds of the Isles. James IV occupied the castle when he tried to subdue the MacDonalds in the late 15th century. MacLean of Duart Castle captured the MacIan chief and then besieged Mingary using the guns of a Spanish galleon, the Florida, which had taken refuge in Scottish waters to escape the rout of the Armada by the English. However the galleon blew up and sank in Tobermory Bay. The Campbell Earls of Argyll took possession of Mingary around 1612 but it was then taken by Alasdair Colkitto MacDonald in 1644 for the Royalist cause. However, only two years later David Leslie recaptured the castle for the Covenanters and returned it to the Campbells. In 1696, all of Ardnamurchan, including Mingary, was given to Alexander Campbell of Lochnell, who set about a series of improvements to the castle which hid most of the remaining 13th century features.
Government troops garrisoned Mingary during the Jacobite Rebellion of 1745 and it was here, in 1746, that the Jacobite MacDonalds of Glencoe surrendered to the government in the form of the Campbells. The castle was probably still habitable in 1848, but fell into ruin thereafter.