Hey. Let me help you on this one.
If we look at the 38th parallel in Asia, we will see a significant location there dividing North Korea and South Korea. It's "Korean Demilitarized Zone", or KDZ for short.
It's very narrow (4 kilometers), yet long enough to divide Korean Peninsula in half (250 kilometers).
It was built just after the Korean war, and the actual wall was finished by 1953. To this day, this is one of the most heavily guarded areas on Earth. Both North Korea, and South Korea are guarding it heavily, since the relationships between these two countries are simply terrible.
