Freely accessible 24/7.
No admission fee.
More information on visitseoul.net http://www.visitseoul.net/en/article/article.do?_method=view&art_id=772&lang=en&m=0004003002002&p=03
Address San 4 Hongji-dong, Jongno-gu, Seoul, South Korea
Coordinates 37°35'54.424" N 126°57'24.149" E