possibility of launching combat aircraft from the mountain air base. High costs and technical difficulties prevented these plans from being realised. The idea of using roads as runways was later part of the design demands for the Swiss motorway network. Taiwan Chiashan Air Force Base, located in Hualien, has an extensive underground hangar system which can accommodate two hundred aircraft. Chihhang Air Base in Taitung County can accommodate eighty aircraft in underground hangars. Former Yugoslavia The "Objekat" series of military installations can be found in secluded but strategically important areas within the former Yugoslavia, and the construction of these military bases were initialized by the SFRJ's defence ministry. During the Yugoslav Wars, most of these bases were used by the Serbs in certain operations, but due to extenuating circumstances imposed by the Croat forces, they were destroyed and later rendered useless for military use. Nowadays, they are popular for urban exploration, however it is risky due to the chances of anti-personnel landmines being located in unexplored areas. However, some were spared the destruction due to other circumstances where the Serbs did not control these installations. An example of some that are still in use to this day is the D-0 Armijska Ratna Komanda nuclear bunker in Konjic, however the latter was turned into an art complex, but is still owned by the Ministry of Defence of Bosnia and Herzegovina. The largest underground hangar complex in former Yugoslavia was at Željava Airport near Bihać, with enough space for 80 MiG-21s. Slatina Air Base, located at Pristina International Airport, contained the second largest. North Korea There are at least twenty major airfields with underground hangars in North Korea, including Onchon air base, Kang Da Ri Airport and Sunchon Airport. See also Highway strip References External links Armeeschulfilm über die Schweizer Flugzeugkaverne "Underground Hangars to Protect War Planes" Popular Mechanics, September 1937 Underground hangars Military airbases