local government area would later be known as Town of Charters Towers and City of Charters Towers, before being absorbed into the Charters Towers Region. Charters Towers Post Office opened on 17 May 1872. A 20 head of stamps mill began ore-crushing operations on 16 July 1872. The Venus Battery continued to be used by small mine in the region until 1971. The unique site remains intact today, together with a cyanide treatment plant and assay office. On Sunday 10 August 1884, the new Charters Towers District Hospital opened. During 1888–89, the Charters Towers Stock Exchange and Royal Arcade were constructed at the northern end of Gill Street for local businessman and civic leader Alexander Malcolm. By 1917, gold mining became uneconomical. During World War I, labour was hard to find, and as the mines drove deeper, ventilation and water problems arose. This production decline was similar across Australian gold mines, with rising costs and a fixed gold price eroding profitability. The town entered a long period of relative stagnation and little further development has occurred since. The Charters Towers gold field produced over 200 tonnes (6.6 million troy ounces) of gold from 1871 to 1917. The gold is concentrated into veins, and was Australia's richest major field with an average grade of 34 grams per tonne. The grade was almost double that of Victorian mines and almost 75% higher than the grades of Western Australian (Kalgoorlie) gold fields of that time. During World War II, Charters Towers was the location of RAAF No.9 Inland Aircraft Fuel Depot (IAFD), completed in 1942 and closed on 29 August 1944. Usually consisting of four tanks, 31 fuel depots were built across Australia for the storage and supply of aircraft fuel for the RAAF and the US Army Air Forces at a total cost of £900,000 ($1,800,000). Beginning in June 1943, Charters Towers was also the location for a major USAAF chemical bomb depot operated by the 760th Chemical Depot Company (Aviation). The depot contained bombs filled with mustard agent, cyanogen chloride and other toxic chemicals. In addition to maintaining the depot, the 760th cooperated with the Australian Chemical Warfare Research Unit to conduct research on bomb design and delivery techniques. Late in 1944, the depot and its contents were moved to Oro Bay, New Guinea. In the , Charters Towers had a population of 8,120 people. Heritage listings Charters Towers has a