The ruins of Buchanan Castle are situated west of the village of Drymen, close to the ruins of the ancient Place of Buchanan.  The castle was built by the 4th Duke of Montrose and is thus unconnected to the Buchanan Clan.

However, the original castle on the site was the ancestral seat of the Clan Buchanan but it passed to the Graham's in the 17th century.  The castle burned down in 1852 and the current building was built by James Graham, 4th Duke of Montrose, and completed in 1855.