beijing chinese pinyin cold war era bomb shelter consisting network tunnels located beneath beijing china referred underground great wall built purpose military defense complex constructed anticipation nuclear war soviet_union sino soviet relations worsened officially reopened visitors allowed tour portions complex described dark damp genuinely eerie closed renovation february location tunnels run beneath beijing city center covering area square kilometres metres surface time entrances complex hidden shops main streets entrances demolished blocked reconstruction known remaining entrances include west street district history height soviet chinese tensions chinese chairman ordered construction border conflict designed withstand nuclear conventional attacks complex protect beijing population allow government officials evacuate event attack city government claimed tunnels accommodate beijing million inhabitants completion complex equipped facilities restaurants schools theaters factories roller skating grain oil warehouses mushroom cultivation farm potential sites water wells easily dug needed elaborate ventilation systems installed shafts sealed protect tunnels inhabitants poison gases water proof thick concrete main gates constructed protect tunnels attacks nuclear official disclosure actual extent complex speculated tunnels link beijing landmarks important governmental buildings great hall people military bases outskirts city asserts supposedly link areas central beijing district addition rumoured residence secret nearby leading tunnels event nuclear attack plan half beijing population underground half tunnels built local citizens including school students volunteer duties portions dug help heavy machinery centuries old city walls towers gates including old city gates destroyed supply construction materials complex complex completion utilized locals ways tunnels remain cool summer warm winter busy streets portions complex refurbished cheap hotels transformed shopping business centers theaters complex intended purpose fully abandoned local authorities perform water checks pest control tunnels regular basis tourist attraction complex officially opened closed renovation february open visitors allowed tour portions complex popular foreign tourists remained virtually forgotten local citizens entrances foreign visitors entered approved sections accessed small shop south square west street tour groups enter free charge prior permission individual tourists group charged official tour took visitors small circular stretch inside complex visitors major landmarks accessible tunnels square chambers labeled original functions cinemas hospitals portrait seen amidst murals locals dig tunnels fading accumulate grain people prepare war prepare famine rooms beds decayed cardboard boxes water seen areas open tourists visitors official tour pass functioning silk factory underground staff meeting rooms complex given demonstration process obtaining silk chance buy tourists shop operated state owned china silk company
Underground City (Beijing)