Head down to City Hall's basement to reach Citizens Hall, a multipurpose space with an interesting mix of multimedia art exhibitions, design shops and a fair-trade cafe. There's also a 21st-century version of Speakers Corner and Media Wall where locals can express their views. Pick up a map and guide from its information desk.
Also here is Gungisi Relics Exhibition Hall, a glassed-in archaeological site displaying items dating from the Joseon dynasty unearthed during excavation of the complex.