The DMZ, which runs across the Korean Peninsula, is 248 kilometres long and the 4 kilometres wide. Created as a buffer at the close of the 1950-53 Korean War, it's jointly overseen by the American-led UN Command and North Korea.
At the height of the Cold War, listeners would notice some bizarre broadcasts over the waves. It would range from weird melodies and recitals to sound of several beeps, people counting random numbers in different languages and creepy voice of a child reciting letters in English. These were known as 'Numbers Stations'.