Long story short, I am going to be staying with a friend in Seoul for about 3 weeks in December. We have several things planned out together (e.g., Gyeongbokgung, Korean BBQ, Gwangjang Market, Nami Island, etc). However, my friend is going to be working most of the days I'm over there, so I need to find some stuff to do to occupy myself while my friend is at work. I'd really appreciate some suggestions for interesting things I can do in Seoul (or within a day-trip distance from Seoul) that are unique and not blatant tourist traps. It doesn't have to be super exciting stuff either: just things to help occupy my time as I wait for my friend to get off work. I've thought of trying out a jjimjilbang (public bathhouse) and making my own name stamp/seal.