Duart Castle or Caisteal Dhubhairt in Scottish Gaelic is a castle on the Isle of Mull, off the west coast of Scotland, within the council area of Argyll and Bute. The castle dates back to the 13th century and is the seat of Clan MacLean.
In 1350 Lachlan Lubanach Maclean of Duart, the 5th Clan Chief, married Mary, daughter of John of Islay, Lord of the Isles and Duart was part of her dowry.
In 1647, Duart Castle was attacked and laid siege to by the Argyll government troops of Clan Campbell, but they were defeated and driven off by the Royalist troops of Clan MacLean.
In September 1653, a Cromwellian task force of six ships anchored off the castle, but the Macleans had already fled to Tiree. A storm blew up on the 13 September and three ships were lost, including HMS Swan.
In 1678, Archibald Campbell, 9th Earl of Argyll, son of the Marquess of Argyll, successfully invaded the Clan MacLean lands on the Isle of Mull and Sir John Maclean, 4th Baronet fled the castle and withdrew to Cairnbulg Castle, and afterward to Kintail under the protection of the Earl of Seaforth.
In 1691 Duart Castle was surrendered by Sir John Maclean, 4th Baronet to Archibald Campbell, 1st Duke of Argyll. The Campbell clan demolished the castle, and the stones from the walls were scattered. Donald Maclean, 5th Laird of Torloisk used some of the stones to build a cottage for his family close to the site of the castle.