The lower part of a chapel built by James III, housing the shrine of St Triduana, a Pictish saint. The Hexagonal vaulted chamber is unique. The chancel and apse of this lovely building are 15th-century. The transepts and steeple were added by the widow of the Lord Seton who was killed at Flodden in 1513. Set on the edge of the cliffs, looking out to the Bass Rock, this formidable castle was a stronghold of the Douglas family.
Display includes replica guns.
The tower and transepts of a church built by the Knights Hospitaller of the Order of St John of Jerusalem in the 13th century, much altered.