Byres Castle is possibly more accurately described as a bastle rather than a castle. Whatever its true classification, it’s a small but substantial structure measuring around 6.3m long by 5.2m wide, with walls 0.7m thick.
Now in ruins, it consists of two storeys. The ground floor level is vaulted and features narrow slit windows in the north-east and south-west walls, with a larger square window in the south-east wall. Access is provided by a doorway in the south-west wall.
The first floor features a fireplace but is now unroofed.
The present structure is thought to date back to the 16th century. During the Rough Wooing the English are said to have dismantled Byres in 1548, and it was probably rebuilt in its current form following the English departure from Haddington in 1549.
It has been speculated that some of the stone from Byres was used to build Garleton Castle nearby in the 16th century.
The existence of an earlier castle is proved by the fact that the title of Lord Lindsay of The Byres was created in 1445.