Ferniehirst Castle is a 15th century tower which was extended in subsequent centuries and is the seat of Clan Kerr.

The Kerrs were present in the Borders from the late 12th century and almost certainly earlier, the first of the name to appear on record being John Ker of Stobo in 1190. By the 13th century a branch of the family had settled at Kersheugh within a mile of Ferniehirst.

When the first castle at Ferniehirst was built is not clear. The first mention of a stone castle is around 1470 which is said to have been built by Sir Thomas Kerr of Smailholm, son of Andrew Kerr of Cessford, who married Margaret Kerr, daughter of Thomas Kerr of Kersheugh. However this castle was almost certainly built on the site of an earlier structure, probably also in stone and perhaps replacing an earlier tower made from wood.

The castle’s position in the Borders meant that it suffered at the hands of invaders, particularly in the 16th century, however it was remodelled and extended in 1598 by Sir Andrew Kerr. Further work took place in the 17th century at which time the Great Hall was remodelled.

By the 18th century the castle was dilapidated however it was re-roofed and repaired around 1830 and in 1890 a major restoration was undertaken. In 1934 it was leased for use as a hostel by the Scottish Youth Hostels Association but during the Second World War it was commandeered to provide accommodation for troops. After the War it reverted to being a hostel until 1984. In 1988 Peter Kerr, 12th Marquess of Lothian, commissioned another major restoration and reverted to being a family home.

To the east of the castle are a pair of buildings flanking the main approach. These have been interpreted as possible bastle houses and while one is a roofless ruin its northern neighbour has been restored for use as a visitor centre.