Standing 248 meters high, Mt. Yuntai is the highest mountain in Nangan. It is ranked the 98th among the Hundred Small Mountain Peaks in Taiwan. Reaching the top of the mountain, one can get the best view of Matsu archipelago and Bei Jiao Peninsula in Mainland China. To correctly interpret its military intelligence, to familiarize the deployment of the communist army in Mainland China, Matsu Defense Command launched the construction of the Military Intelligence Building in 1996. Meanwhile, considering the tourism development in Matsu, Matsu Defense Matsu National Scenic Area Administration had asked for the Defense Command's agreement to renovate this building and reopened it for tourists on 7th, November 2010.