The ruined building is mainly 15C and was part of a college founded by Archibald the Grim, 3rd Earl of Douglas on the site of a 12C Benedictine convent. The chancel has no roof but contains coats of arms and a few fine sculptures including the ornate, early 15C tomb of the 4th Earl's wife, Princess Margaret, daughter of Robert III. The nearby remains of a garden with a complex layout are overlooked by a Norman mound.