The Demilitarized zone.
Some background:
Located roughly along the 38th parallel the Demilitarized zone, or DMZ seperates The Republic of Korea (South Korea / RoK) and The Democratic(!) People's Republic of Korea (North Korea). Side note. South Koreans call Korea 대한민국 (Dae han Min Guk) while Northerners refer to the Penninsula as 조선 (Chosun)
The DMZ is 4km wide stretching right across the Penninsula from the west to the east coast. If you were to travel north from Seoul you would first cross the Southern Limit Line, travel 2km to The Military Demarcation Line (MDL) - the actual line between North and South - travel a further 2km cross the Northern Limit Line and into North Korea proper.
Stradling the MDL is the Joint Security Area or JSA manned originally by US and Rok military personnel on the south and DPRK soldiers or the Korean People's Army (KPA) on the North. This year security on the southern part of the JSA was handed over to the RoK. The JSA has been the scene of many meetings between the two sides from the original armistice talks at the end of the Korean war in 1953, to meetings concerning economic aid for the north, ICRC (Red Cross) meetings and even International Olympic Committee (IOC) meetings.

A KPA soldier stationed in the JSA. While it is prohibited to take photos within the DMZ the JSA - under United Nations command is relativly open and one can take photos freely.
Contrast the above with this picture of a KPA guard in winter. The uniforms of the KPA reflect their soviet heritage.
The JSA is also known as Panmunjom (판문점), an actual village destroyed during the 1950-1953 conflict. It now covers about 800metres square and consists 24 buildings housing the United Nations Command Military Armistice Commission and various meeting spaces. Prior to entering the JSA one passes through Camp Bonifas - home of the United Nations Command Security Battalion which holds the motto "In Front of Them All" which in the days of the cold war refered to the fact that the DMZ was very literally the warmest of fronts in which The West (Primarily the Americans) faced down the threat of Communism. Nowadays it's a bit farcical in that the joint forces of the US and the RoK could wipe North Korea off the map using only conventional forces in a matter of days - if not hours.
The JSA with Panmungak in the background
Tours of the JSA are conducted by US personel - usually of Spec. or Cpl rank. While informative they are evidently scripted and I have had the same jokes delivered on tour 8 months apart by different guides.
There have been a number of cinematic representations of the JSA and the DMZ - most recently the James Bond film Die Another Day - which is very UNrealistic, and the Korean film JSA which is a good replica. With the exception of additions by The Hyundai company of a large meeting complex on the South Side and extensions to the Panmungak complex on the North, the buildings and camp Bonifas are all 1960 era buildings - buildings that one would expect to crumble quickly under artillary attack from the North.
Passing through the DMZ is a unique experience. Especially for a New Zealander who doesn't see automatic weapons, Tank traps and mine fields on a regular basis. Hell we have a pitiful army, and no airforce, And one only really sees the Navy when junior officers are attending engineering lectures at varsity. The DMZ has been the scene for a number of almost surreal incidents, including the defection of a soviet translator (?) in November 1984. Said Russian crossed the MDL from the Northern side while on vaction and defected to the West only after several KPA personnel chased after him shooting wildly killing a couple of people on the way.
Mines!
Perhaps the most notorious incident happened in August 1976 when two US personnel were hacked to death with axes by KPA personnel while the Americans were attempting to remove a Poplar (?) tree disrupting line of sight around the bridge of no return. (One, Cpt Bonifas - posthumously made Maj.- had Camp Bonifas named after him.) Two days later the US military went to DefCon 2, with their entire force on standby while army engineers succesfully removed said tree.
There now stands a memorial to Maj. Bonifas and 1Lt. Barrett where the stump of the now infamous tree once stood. (The picture is a bit askew as tours are not permitted to exit the tour bus at this point
The Bridge of No Return
This is where all POWs were repatriated to the North or South at the end of the 1950-1953 conflict. Upon returning UNC soldiers were cleaned up, given new uniforms and a bowl of ice cream! Interestingly The Bridge of No Return remains the only road link between Seoul and Pyongyang.
This photo taken in July shows how close things are and how close the communists can get, proving that the UNC Security battalion truely are "In Front of Them All!"
Bibliography
Kirkbride, W.A. 'Panmunjom. Facts About the Korean DMZ', 5th ed., Hollym, 1998.
Very few people can say they have a JSA Zippo now. Can they?
Click on Pictures to enlarge.