I took the one day tour to visiting the south/nort Kora border, it was fascinating and interesting. You can feel the tension between the south and north. In the video, you will also see the closest North-Korea village (fake city?) of the South Korea - The village is called "propaganda village" or the official name "Kij?ng-dong" and a north korean soldier.
If you're planning to go to Seoul, take the tour, you will not regret it!!!