activities. It is where security missions are carried out by the Biryong Unit who are on alert 24/7. With the telescope at the observation post, visitors can see North Korean posts and barbed wire fences on the front line as well as the wide Yeoncheon Plain, which is currently inaccessible as it is now inside the Demilitarized Zone. In addition, visitors can take a tour of the First Tunnel of Aggression from the Sangseung Observation Post. Since the actual First Tunnel of Aggression is located within the Demilitarized Zone, and thus cannot be viewed by the public, a model in the actual size is built at the Sangseung Observation Post, the nearest observation post, to allow visitors of Sangseung Observation Post to take a tour.