Kim Jong Un's father Kim Jong Il had secret underground tunnels linking his North Korean palaces, holiday homes; what did his hidden world look like? - The Economic Times
Kim Jong Il's office complex in central Pyongyang was also mentioned in the report. It was a heavily fortified building made of reinforced concrete. It had thick walls and large automated gates. It reportedly said the underground passages connected the office to nearby residences. One such route linked the office to Residence No. 15. The passage was reportedly 100 metres below ground.