Triermain, now just a ruin, lies just a few miles west of Gilsland and was build in the 14th century to defend the Barony of Guilsland from attacks by the Liddesdale Armstrongs and Elliotts during the Border Reiving days. It is thought to be the inspiration for a ballad by Sir Walter Scott called ‘The Bridal of Triermain’, and is said to be haunted.