Small castle on a peninsular ravine-edge sited on S bank of Girvan Water. Rubble built with crowstepped gables and slated roofs. Nucleus small square tower of late 16th century date, 26' by 21', 3-storey and basement with pepperpot turrets at NW and SE and (originally) a circular stair tower at NE. Lower wing running E-W built onto N gable, 1628, 2-storey and basement producing L-plan castle of stepped profile. N wing ruinous by early 19th century, rebuilt 1857 to design by the then owner Spencer Boyd and the Glasgow civil engineer A G Thomson, S gable of original tower house designed same date. New work included large circular stair corbelled out at upper levels and similar in profile to original NE tower, but with machicolated parapet and stepped crenellation. Round arched doorway with quatrefoil light at sculptured tympanum, curved glass hood on ornamental metal cantilever brackets. Boldly battered plinth courses. N elevation relatively plain with pedimented dormerheads. Tall single storey hall block to E, William Bell Scott, 1883; buttress feature surmounted by owl and mullioned window on S elevation, twin lancets at E gable, lower link with parapet and belfry feature to main castle crowstepped gable with archway to service court at lower level. Important interior work:
ENTRANCE VESTIBULE: small with timber armorial and Gothic black letter inscriptions.
STAIR: turnpike with major Pre-Raphaelite mural cycle of Kings Quair by William Bell Scott containing portraits of Alice Boyd, the Rossettis and Scott himself, 1859 onwards, wax spirit fresco, partly painted on zinc. Separate schemes of painted decoration at window splays and passages to bedrooms.
LIBRARY: 1st floor of original tower; large segmentally arched stone chimneypiece with stone hood, beamed ceiling, gothic inscriptions, arabesque panels at the window reveals, parts of decorative frieze, wrought-iron curtain rail and panel of carving framing on watercolour.
ANTE-ROOM TO DRAWING ROOM: (now dining room) 2nd floor of original tower; Dutch gilt leather dado, stencilled walls, inset painted panel in ceiling.
DRAWING ROOM: (now dining room) 2nd floor of original tower. Designed as a setting for tapestries still in situ: nook-shafted chimneypiece of 1857, mural of The Twa Corbies by William Bell Scott in window recess, beamed ceiling.
UPPERMOST BEDROOM ('The Windy Room' or 'Christina Rossetti's Room') 3rd floor of original tower. Coved with important scheme of mural decoration by Christina Rossetti of trees with falling autumn leaves and reused ancient woodwork.
MAIN BEDROOM (Laird's or Alice Boyd's) 1st floor of 1628 wing. Chimneypiece of ancient woodwork, painted ceiling of branches and leaves.
MIDDLE BEDROOM: (William Bell Scott's) 2nd floor of 1828 wing. Coved with important decorative frieze, partly on painted paper, with paintings of animals, ancient woodwork on chimneypiece.
HALL CORRIDOR: decorative woodwork, designed as a setting for tapestries.
HALL: timber-lined interior with open timber roof, original hanging lamps; elaborate chimneypiece with granite inset; painted decoration at window reveals.
Small 2-storey block of stable offices of 19th century date, walled garden and sundial with wrought-iron gate given by Christina Rossetti, terracing.