Tour Scotland video of Buchanan Castle west of the village of Drymen. The house was built by the 4th Duke of Montrose in 1854. The original structure, the ancestral seat of the Clan Buchanan, had burned down in 1852, and Montrose commissioned William Burn to replace it. Burn designed an extravagant manor in the Scottish baronial style. This new house replaced Mugdock Castle as the official seat of the Clan Graham.