 The barracks consists of two levels , with rifle firing holes on all sides . Iron shutters closed on the inside and were locked with wooden beams . In 1885 the <unk> facing the manning parade was enclosed with wooden shutters to keep the weather out . These shutters were removed during 20th @-@ century restoration work and the <unk> returned to original condition . The roof was at first flat timber overlaid by 12 inches ( 30 cm ) of lime concrete . This first roof leaked and an iron roof was added in 1885 . The first floor of the barracks contains the officer 's rooms and troop 's barracks room . Its eastern ( outer ) wall is not flat , incorporating a design feature known as " <unk> " , which opens the field of fire from the rifle holes . Some of the firing holes were <unk> in during the 1930s ; this has been only partly rectified during restoration . 
