The Keep, Glencorse Barracks, Penicuik

The Keep at Glencorse Barracks is a three-story, z-plan former store and armoury, likely dating to circa 1875. Constructed of bull-faced yellow sandstone with stugged dressings and chamfered arrises, it features three-by-three-bay elevations and diagonally opposed, clasping corner towers. The ground storey of the corner towers is battered, with a further battered band course above the ground floor and a deep, crenellated parapet with gabled coping to the wallhead. Each face of the square core is regularly fenestrated, with a window in each floor and bay. Corner stair towers are present to the north and south corners, each with doors to the inner returns, stepped arrowslit windows to the stairs, and regular arrowslit windows to the towerheads, which break the eaves and are topped with heavy corbelled crenellations. Metal small-pane glazing is used throughout, with upper hopper panes.

The interior includes cantilevered stone stairs to the towers, now with a later metal handrail, and cast-iron columns within the stores.

The Keep is a dominant and powerful centrepiece within the barrack complex. It likely dates to the period 1875-1877, coinciding with the change in site function from a military prison to a brigade depot for southeast Scotland. The design shares similarities with the castellated buildings at HMP Perth.

Originally a military prison completed by 1813 and costing £100,000, the site previously included observation walkways and prison blocks radiating from a principal terrace. These features were likely demolished during the conversion to the central brigade depot in 1875-1877. Greenlaw House was also demolished, although its cellars may survive within the Officers' Mess block to the southeast. Glencorse Barracks remains in military use and forms part of a larger group including the clock tower, a barrack block, a chapel, terrace and stores, memorial lodges, gates, gatepiers and boundary walls.