Deep below the ground is North Korea's beautiful Pyongyang Metro, a bustling subway system where hundreds of thousands of people make their way to and from work every day. The metro is 360 feet below ground, making it one of the deepest subway systems in the world. Some of the stations are so deep, they double as bomb shelters that are protected with heavy blast doors. A ticket to travel on the Pyongyang Metro is cheap, only 5 won, which at the time of writing is about $0.004.

Follow Tech Insider: On Facebook