Sites inaccessible because of location on private or army land
Some newly graded historic military structures stand on private land or inside barracks of the People's Liberation Army, areas that are restricted from public access.
The Bockhara Battery at Cape D'Aguilar, for example, is on PCCW property the public cannot visit without a permit. The battery was destroyed in the second world war, but two circular gun emplacements, two searchlight emplacements, an observation post and two rows of blocks remain.
The public will have a chance to visit the site in May and June by joining two guided tours organised by the Museum of Coastal Defence, which will also visit other sites on south Hong Kong Island.
Another private site is the Central Ordinance Munitions Depot in Shouson Hill. Proposed as a grade-three site, it is now a private wine cellar after serving as a police driving school in the 1970s and a rock storeroom.
The operator, Crown Wine Cellars, won a Unesco heritage award of merit in 2007 for its conservation work. The depot was built by the British to store arms and ammunition before the second world war.
Some 26 military facilities with gradings ranging from one to three are found in the PLA's barracks on Stonecutters Island, while some 30 facilities are situated in Chek Chue Barracks in Stanley.
Asked if the structures are in use and whether they need maintenance, a spokesman for the army's press office said the army had paid great attention to the conservation of the antiquities, and had drawn up internal guidelines specifically for the work.