

Namhansanseong Fortress, Gwangju
The Namhansanseong Fortress (https://map.naver.com/p/entry/place/13490975?place) is a UNESCO World Heritage site atop Namhansan mountain. It really isn't viable getting here unless you have a car, or at least a friend with a Korean licence. Once you get there, you could also trek along the walls (I assume these are the same walls that Korean soldiers fought off the Japanese during Joseon era). It took about half an hour, but the view of Downtown Seoul from up there is definitely something to experience.
After that, we drove down to Cafe Vu by World Green (https://map.naver.com/p/entry/place/1462265629?place). It's a quick 10 minute drive along a river (stream?) dotted by various such cafes. The coffees were pretty good, but the dessert, especially the Nutella Choco Cake, was to die for! Also, the owner has a special affinity to foreigners. He told us all about how he spend years abroad, and even gave use coffee for free. We spent most of our time sitting by the stream or just lounging in one of the many sofas/swings. They also gave us nets and poles, and we managed to catch three fish. We decided to release them back tho, since there was really no real way they'd survive in an aquarium.
Of course it helps if you have a car, but this place is worth a visit even if you have to pay for a cab. Do check it out.