The park is what used to be a fortress. Now it is basically just a hilly area with a moat around it.
The main entrance to the park is marked by the World Peace Gate.
Within the park, there is an archaeological site. It is now within a building to protect it. All you can really see are a bunch of post holes on a dirt floor. There were several dwellings in the area, some built on top of others (so they overlap) One of them has a visible hearth.
There were many birds in the park, mostly sparrows and magpies. I did see one ring-necked pheasant. I could be wrong, but I don't think they are native to Korea. I also saw two rabbits. The black one seemed to enjoy being a distance away from the people (some guy was trying to get close enough to take a pic with his handphone, and scared it away). They other one seemed fairly tame. You could go right up to it to take it's picture. It even jumped up onto a woman's legs when she was taking a pic of it with her phone. As I was leaving, it was getting handouts from a family that was sitting on the nearby benches. I guess that would be the reason for its behavior... tasty handouts.
In Korea, when they build an apartment building, they don't just build one; they build 50 or 100 or so, all at the same time. All around the city, there are sites where apartment buildings are going up. (Those are cranes that you can see in the distance.)