The circumference of this fort (Visit in Google Maps) is 1.8 km, which, I'm told, is approximately the same size as Camp Wright in Afghanistan. I'm also told that some people at Camp Wright think their base is super small, but Haemi Fortress was big enough to be used as a military base in Korea for about five hundred years, including almost a year when famous Korean general Lee Soon-Shin was stationed here.
This fortress was also where a thousand or so Catholics were killed in the 1860s, back when Korean society was known for being particularly open minded. We visited the Catholic shrine nearby back in 2010 which commemorates the martyrs.
These days, the fortress is open for Sunday afternoon picnics and other non-military activities.