Prendo link e titolo pari pari da un altro sito, a mio avviso merita: http://www.earthnutshell.com/stopping-all-stations-the-pyongyang-metro/
Pyongyang Metro is the deepest metro system in the world at 110 metres, conveniently doubling as a nuclear bunker, just in case. It’s an almost four-minute descent to reach the train platforms , and, to the top and bottom of the escalators, the hallways are protected by thick steel blast doors. You can see these most notably at Yonggwang and Kaeson stations. alla faccia...http://www.korea-dpr.com/
