DMZ

« The Korean Demilitarized Zone (Hangul: 한반도비무장지대; Hanja: 韓半島非武裝地帶) is a strip of land running across the Korean Peninsula that serves as a buffer zone between North and South Korea. It is 250 kilometers (160 miles) long, approximately 4 km (2.5 mi) wide and is the most heavily militarized border in the 

world” (Eg: Wikipedia)

 DMZ and North Korea are kind of "taboo" in SK. However, this a unique place in the world, so if you have ever the opportunity to visit it, don't hesitate this is totally worthwhile. You can feel the deep tension between the 60 years old enemies. You can go on the boarder by yourself; however there are a lot of tour organized which will bring you there for around 60 000wons. Here is one of them: http://cosmojin.com/

The DMZ knows incidents at least once a year in average (exchange of gun fire most of the time) without consequences.