the Argyle Tower built over the Portcullis Gate and the Great Hall restored after years of use as a barracks. A new Gatehouse was built in 1888. During the 19th century, several schemes were put forward for rebuilding the whole castle as a Scottish baronial style château. Work began in 1858, but was soon abandoned, and only the hospital building was eventually remodelled in 1897. Following the death of Prince Albert in 1861, the architect David Bryce put forward a proposal for a keep as a memorial, but Queen Victoria objected and the scheme was not pursued. In 1905, responsibility for the castle was transferred from the War Office to the Office of Works, although the garrison remained until 1923, when the troops moved to Redford Barracks in south-west Edinburgh. The castle was again used as a prison during the First World War, when "Red Clydesider" David Kirkwood was confined in the military prison block, and during the Second World War, when downed German Luftwaffe pilots were captured. The position of Governor of Edinburgh Castle, vacant since 1876, was revived in 1935 as an honorary title for the General Officer Commanding in Scotland, the first holder being Lieutenant-General Sir Archibald Cameron of Lochiel. The castle passed into the care of Historic Scotland when it was established in 1991, and was designated a Scheduled Ancient Monument in 1993. The buildings and structures of the castle are further protected by 24 separate listings, including 13 at category A, the highest level of protection for a historic building in Scotland, and special care was taken when installing 31 kW solar panels on the roof of the War Memorial, obscured by its parapet. The Old and New Towns of Edinburgh, a World Heritage Site inscribed by UNESCO in 1995, is described as "dominated by a medieval fortress". Description Edinburgh Castle is located at the top of the Royal Mile, at the west end of Edinburgh's Old Town. The volcanic Castle Rock offers a naturally defended position, with sheer cliffs to north and south, and a steep ascent from the west. The only easy approach is from the town to the east, and the castle's defences are situated accordingly, with a series of gates protecting the route to the summit of the Castle Rock. Outer defences In front of the castle is a long sloping forecourt known as the Esplanade. Originally the Spur, a 16th-century