Here you thought that only the villians in Bond films had extensive bases with underground railroads. Turns out that "Dear Leader" has one too
Built to link secret underground military facilities, the Pyongyang Metro is nevertheless an important part of the transport infrastructure in the capital of North Korea (officially, the Democratic People’s Republic of Korea or DPRK). It includes secret government-only lines about which very little is known. Its station architecture is among the most attractive in the world. However, relatively little is known about the Metro outside the country, as few visitors are able to investigate the system. In recent years North Korea’s economic crisis has affected Metro operation, and service has apparently been reduced significantly. Yet in recent years replacement trains have been bought from Germany, and plans still exist to expand the system, particularly in the direction of other military command posts.