18 ft, standing two storeys high, with a central staircase tower projecting, and rising one storey higher. The entirely ruinous interior has extensive brickwork and concrete supports; the ground floor is vaulted. The entrance door is unusually wide and low, with carvings above. The building is domestic, rather than military in style, with corbie-stepped gables and stones laid in courses. In 1895 Smith records the castle ruins as having been recently restored, suggesting consolidation work. Hooks for window shutters survive at the first floor level. Crow stepped dormer heads were added in the 19th century and windows on the south elevation may have been enlarged at this time. The buildings rear wall has been greatly altered to give access to another building circa 19th century. Close and Riches see the layout to be a mirror image of Crosbie Tower that may have been inspired by Monkcastle. The Rev. William Lee Kerr in 1900 described the castle as ruinous and made reference to cellars "which can still be traced underground." No such cellars are visible today (2011). Doocot and sundial Nearby the ruins there are said to be the jumbled remains of an ancient dovecot, in appearance more like an ice house. The OS map shows a formal garden to the south of the castle ruins. Rob Close sees similarities with Crosbie Castle, Prestwick. A facet-head sundial of the 17th or 18th century is recorded to have existed at 'Monk Castle', but listed as lost in 1987. Monkcastle House Alexander-William Miller built the surviving Monkcastle House nearby, circa 1820, probably designed by the architect David Hamilton and similar in architectural style to Swindridgemuir.Monk Castle. Gazetteer for Scotland. Retrieved: 2010-10-03 John Campbell Arbuthnott, 16th Viscount of Arbuthnott married in 1949 Kathleen Maude Eginton Grant, only child and heiress of Charles Edward Grant of Monkcastle. Monkcastle House is in 2010 the private dwelling of Sir Charles Stuart-Menteth, 7th Baronet of Closeburn and Mansefield. The estate In 1866 the estate amounted to around 360 acres. William Campbell Miller died intestate at the age of fifteen in 1857. At the time of his death his town residence was Saxe Coburg Hall, Edinburgh, and the following properties were listed in the inventory of his estate: Baidlandhill and Windyedge in the parish of Dalry; Hill of Fergushill, Kilwinning parish; Craighead, and Craighead Mill; High Monkcastle and Low Monkcastle; Hillend; Mansion House Grange; Cottages at Old House; Crofthead;