Eunpyeong-gu Library

It’s a hilly trek up to this district library at the western terminus of line 6. The terraced rooftop spaces are the highlight of the uniquely designed building, which received the 2001 Korea Architecture Award. Each of the terraces has a few shaded nooks with benches for peaceful reading or quiet conversations. But don’t think cozy means cute—the feel here is almost post-apocalyptic, with the exposed cement building tucked up against the greenery of Bulgwang Mountain on one side and its blocky, turret-like terraces overlooking the city on the other. Tip: Currently, only the lower rooftop level is open, but if they’re not too busy and you ask nicely, the staff will unlock the gates to the top level and let you snap some photos.