DMZ stands for demilitarized zone, and it's the no-man's land border between North and South Korea. Heavily guarded and mined, the strange area can be visited, but only on an official, guided tour (the USO operates a popular one).
Description
The official area is about four kilometers wide and is formally known as the JSA or Joint Security Area. The closest town is Panmunjom.
Tours include a visit to a North Korean gift shop and the very strange Military Armistice Commission Conference Room, which straddles the Military Demarcation Line. Visitors can step over the border into North Korea, while inside the cross-border room. The site and surrounding area also has several observation towers, parks, and museums.
Official site: http://www.nseoultower.co.kr/eng/