Just a year before the Japanese invasions of Korea broke out, in 1591, Admiral Yi Sun-sin was appointed commander of the Jeolla Left Naval Base — the headquarters of the left-wing defense line of Joseon's navy, based in what is now Yeosu. After his appointment, Yi Sun-sin stayed in a pavilion called Jinhaeru, using it as his base to refit his fleet and prepare turtle ships against the coming Japanese invasion. The unbroken string of naval victories Yi Sun-sin would go on to win throughout the war had its origins in the preparations made at this very spot.
Jinhaeru burned down during the second phase of the war, the Jeongyu Jaeran invasion of 1597–1598. The year after the war ended, in 1599, Yi Si-eon, the Naval Commander of the Three Provinces, built a new guest hall on the site of the destroyed Jinhaeru and named it Jinnamgwan. The building was designated Korean Treasure No. 324 in 1963, then elevated to National Treasure No. 304 in 2001. Today, Jinnamgwan is the largest surviving single-story wooden building in Korea. It reopened in 2025 after a ten-year restoration project. At the very spot where Yi Sun-sin made his final preparations before going to war, the largest wooden building that lets us gauge the scale of Joseon-era wooden architecture now stands.