Most of the denoted points-of-interest were part of the same complex: Nakseongdae Park (낙성대공원). It seemed to be a kind of grand shrine that doubles as a kid's park. The shrine part of it revolves around a Korean general (or warlord) Kang Gam-Chan who fought the Mongols in the 1000s AD.
Most of the park seems, on weekends, to be occupied by kids riding small bicycles or recklessly piloting electric-powered toy cars. Their wild swerving-around in those little cars cannot help but remind one of a certain stereotype...
Walking past the above-described park dedicated to the memory of a long-dead general, something calling itself "Seoul Science Park" materializes on the left. It's a sprawling complex surrounded by some short walking trails in the hills.
Next to this "Seoul Science Park" there also seems to be a farm plucked right out of rural Jeolla and plopped down in Seoul. I conclude that it is an experimental farm (whatever that means). Why else would it be there?
The most interesting feature of this place was its mini-planetariums (or, "planetaria", if you insist). At the top of the hill overlooking Seoul Science Park, there is an observatory -- that silver structure in the above. It is surrounded by little blue spheres (one is below), into which a person can put his head. On the inside of these spheres are compelling re-creations of the night sky. They are soundproof and "lightproof", so the sensation I got was of being alone on a cloudless, pitch-black night in a very-non-light-polluted area.