While walking around Suwon and its beautiful fortress wall, you will come to Dongnamgangnu...the Southeastern pavilion near the southern gate.
Gangnu is a pavilion-like structure located on a relatively high place of the fortress walls, where troops were able to rest and keep watch of hte surrounding areas. During extraordinary situations, it served as a command post. Among the four such pavilions, Dongnamgangnu has the widest angle of view in and out of the fortress. Located opposite the Namgongsimdon (Southern Watchtower), it was built to defend the sections near the Namsumun (Southern floodgate).
As a previous cache made its way in to the history books, it opened up this beautiful are once more for this cache.
You can access this cache and you walk along most of the fortress wall for free, but be aware that certain parts of the fortress do require a minor admission fee of 1,000 won.