It lies 3 miles (5 km) NNE of Oban, situated on a platform of conglomerate rock on a promontory at the south-west of the entrance to Loch Etive, and is surrounded on three sides by the sea.

[5] Guarding a strategic location, it was built by the MacDougall lords of Lorn, and has been held since the 15th century by the Clan Campbell.

Dunstaffnage is maintained by Historic Environment Scotland, and is open to the public, although the 16th century gatehouse is retained as the private property of the Captain.

Before the construction of the castle, Dunstaffnage may have been the location of a Dál Riatan stronghold, known as Dun Monaidh, as early as the 7th century.

A later keeper, John Stewart of Lorn, was a rival of Alan MacDougall, and was stabbed by his supporters on his way to his marriage at Dunstaffnage Chapel in 1463, although he survived long enough to make his vows.

Although MacDougall took the castle, he was ousted by James III, who granted Dunstaffnage to Colin Campbell, 1st Earl of Argyll in 1470.

The Campbells were loyal allies of the royal house, and Dunstaffnage was used as a base for government expeditions against the MacDonald Lords of the Isles, among others, during the 15th and 16th centuries.

In 1810 an accidental fire gutted the gatehouse, and the Captains ceased to live here, moving to Dunstaffnage House some 2 km to the south-east.

[19] In 1958, the 21st Captain and the Duke agreed to hand the castle into state care,[18] and it is now open to the public as a Historic Environment Scotland property.

The walls are of coursed rubble, with sandstone dressings, and stand up to 18 m (60 ft) high, including the conglomerate bedrock platform.

The walls are up to 3 m (10 ft) thick, affording strong defence to this highly strategic location, guarding the entrance to Loch Etive and the Pass of Brander beyond, and today commanding a splendid view.

The north tower, or donjon, is the largest, comprising three or four storeys originally, and probably housed the lord's private apartments.

[20] The west tower is almost internal, barely projecting beyond the rounded corner of the curtain wall, and could only be entered via the parapet walk.

In 1725 the range was remodelled into a two-storey house, accessed via a stone stair, and topped with the dormer windows which now form part of the gatehouse.

This was also built by Duncan MacDougall of Lorn, as a private chapel, and features detailed stonework of outstanding quality.

The chapel was already ruinous in 1740, when a burial aisle was built on to the east end, to serve as a resting place for the Campbells of Dunstaffnage.

The office still exists, and to retain the title (now rather a sinecure without military significance), the incumbent is required to spend three nights a year in the castle.