Following a tip-off from a North Korean defector, on 17 October 1978 South Korea discovered the existence of what is now known as the Third Tunnel of Aggression. It is the closest to Seoul of four such tunnels, secret passageways linking the two territories that were chiselled out of bedrock to prepare for a surprise invasion from the north. There are believed to be up to 20 more still to be found.

It is estimated that the narrow 1.7km-long tunnel would enable over 30,000 North Korean soldiers per hour to make the journey south. Nowadays, there are preventative concrete barricades in place and the tunnel has instead become a popular tourist spot complete with gift shop.

At the mouth of the tunnel stands a statue with the title This One Earth (하나 되는 지구). It is one of a number of pro-unification artworks and sculptures found on both sides of the Korean Demilitarized Zone (DMZ), the heavily-guarded no man’s land that divides the countries. As with the Statue of Brothers at the War Memorial of Korea, the split earth indicates the sadness of a country torn in two. Here men, women and children on either side of the divide attempt to push the earth back together, in a symbol of peace and forgiveness.

Image: This One Earth, DMZ, South Korea.