The evolving landscape of the base represents three periods:   As at July 2002, the fabric relating to each of these periods or phases remains essentially intact to document changes in the landscape, which continues to express the original planning and layout of the base during the period 1939–1945. In common with operational changes on other RAAF bases, the Bellman hangars have been modified by the addition of extensions and have in most cases been reclad externally, although the structural frames remain intact. Of the in situ hangars, from 1939–1945, Hangar 172 is the most intact retaining the original sliding door systems intact. The parade gound is now used for car parking and is also used for small storage buildings. RAAF Base Williamtown buildings were listed on the Australian Commonwealth Heritage List on 22 June 2004 having satisfied the following criteria. The evolving landscape of RAAF Base Williamtown, comprising Henderson Road, the road network of the 1939–1945 camp, 1939–1945 buildings and structures (substation and emergency powerhouse, underground fuel tanks, parade ground, tennis courts, Bellman hangars, and associated taxiways, sections of runways 1 and 4 and the pump house) and post-war structures and buildings (the main runway and northern taxiways and hardstanding, additional Bellman hangars, married quarters, the first airmen's dormitory block, stores, test butt, armament preparation units, explosives storage, airmen's dormitory blocks, officer's dormitories, and control tower) is important as the operational and training focus for Australia's jet fighter aircraft. These include the Vampire (1949–1955), Sabre (1955–1964), Mirage (1965–1982) and F/A 18 Hornet (1983–present). Australia's involvement in the Korean War (1949–1951) promoted the development of the base, which in 1945, following the World War II (1939–1945), had been one of ten mainland RAAF bases considered strategically important to Australia's defence, as peacetime base for the RAAF fighter wing. In 1988 RAAF Base Williamtown became the Headquarters for the Tactical Fighter Group. The site was selected for the RAAF in August 1939, when the site was surveyed for an emergency landing ground, a significant factor in its selection being its proximity to Newcastle's steel mills and coal mines. The base is also significant for the use of limited resources through the New South Wales Government's Unemployment Relief Program and the completion of four runways in 1940. Officially opened in February 1941, the base is historically significant for its contribution to the Empire Air Training Scheme as No. 2 Recruit Depot and as No. 4 Operational Training Unit between 1942 and 1945.