Gaewonsa (開元寺) once stood in the southern part of the fortress compound. A description of the temple history can be found on a sign inside and to the right of the "one-pillar" gate (the main entrance): "Gaewonsa was established in 1624 as the main temple to direct the monks who were conscripted from around the kingdom to rebuild Namhan Mountain Fortress, destroyed during the Imjin War with Japan. The temple was destroyed by the Japanese authorities in 1907 and is now under reconstruction."