The first airfield in Belgrade was inaugurated in 1910 in the neighbourhood of Banjica and was initially used by aviation pioneers such as Simon, Maslenikov, Vidmar and ?ermak. Two years later a wooden hangar was built for the Serbian Air Force, which was at the time engaged in the First Balkan War against Turkey. In 1914, the Banjica airfield was the base for the Serbian Air Force squadron and the Balloon Company. After the end of the First World War, the Banjica airfield was used for airmail traffic and included the routes Novi Sad–Belgrade–Niš–Skopje and Belgrade–Sarajevo–Mostar. In 1911 another airfield was inaugurated in Belgrade, in the lower city of the Kalemegdan Fortress at the location of today's Belgrade Planetarium. An airport on the outskirts of Pan?evo, a town located northeast of Belgrade, began its operations in 1923 when CFRNA inaugurated the international route Paris–Istanbul, which was flown via Belgrade. In the same year, on that route, the first ever world night flight occurred. The same year airmail service began operating from the airport. The Pan?evo airport was also used by the Royal Yugoslav Air Force academy. After World War II, the airport was used by the Yugoslav Air Force before it became the airfield of the Utva Aviation Industry after its relocation from Zemun to Pan?evo. Because of the distance from Pan?evo to downtown Belgrade, which at that time required crossing the Danube, a decision was made to build a new airport that would be closer. The airport was planned to be built just across the river Sava, in a neighborhood today known as Novi Beograd. It was opened on 25 March 1927 under the official name of Belgrade International Airport (also known as Dojno Polje Airport). From February 1928, the aircraft owned by the first local airline Aeroput started taking off from the new airport. The airport had four 1,100–2,900 metres (3,610–9,510 ft) long grass runways. The design for a reinforced concrete hangar that was built at the airfield was made by the Serbian scientist Milutin Milankovi?, better known for his theory of climate change. A modern terminal building was built in 1931, while the landing equipment for conditions of poor visibility was installed in 1936. Before World War II, Belgrade was also used as a stopover for some major air races, such as The Schlesinger African Air Race. Besides Aeroput, Air France, Deutsche Luft Hansa, KLM, Imperial Airways, LOT Polish Airlines and airlines from Italy, Austria, Hungary and Romania also used the airport until the outbreak of the Second World War. Belgrade gained further prominence when Imperial Airways introduced inter-continental routes through Belgrade, when London was linked with India through the airport. Belgrade was linked with Paris and Breslau because CIDNA and Deutsche Luft Hansa, respectively, included Belgrade on its routes to Istanbul. By 1931, Belgrade became a major air hub being linked with regular flights with international destinations such as London, Madrid, Venice, Brussels, Berlin, Cologne, Warsaw, Prague, Vienna, Graz, Klagenfurt, Budapest, Bucharest, Sofia, Varna, Thessaloniki, Athens, Istanbul, and also intercontinental links with Cairo, Karachi and India. Starting from April 1941, German occupation forces used the airport. During 1944 it was bombed by the Allies, and in October of the same year the German army destroyed the remaining facilities while withdrawing from the country. The airport was rebuilt by October 1944, and until the end of the war was used by the Soviet Union and Yugoslavia as part of the Allied war effort. Civil transport by Yugoslav Air Force cargo planes from this airport was reinstated at the end of 1945. At the beginning of 1947 JAT Yugoslav Airlines and JUSTA took over domestic and international traffic, and from 1948 Western European airlines resumed flights to Belgrade. A constant increase in traffic and the beginning of the passenger jet era called for a significant expansion of the airport.