Hailongtun is an important relics in the heyday of the southwest toast system, and is also the most complete military castle in China, with excellent architectural art. Tunju is the top of the mountains, the north, east and south three faces the main source of the Zunyi Xiangjiang River "white sand water", are all cliffs, only a small road to the top of the mountain in the southeast. "Zunyi Fuzhi" records that Hailongtun "a single ti is alone, the mountains are consolidated, the left and right around the stream, and the shadow is deep and dangerous." Hailongtun was originally built for the 15th Tuguan Yang Wen of Bozhou Yang to resist the Mongolian army, and because of the beautiful scenery on the Tuen, it is also a trip away from the palace. Twenty-four years of Ming Wanli (1596 AD), Yang's 30th Tusi Bozhou Xuanwei made Yang Yinglong mobilize 80,000 laborers and craftsmen, and spent 4 years, expanding the castle, palace, etc. on the basis of Longyatun built by his ancestors. The buildings were built with a thousand pounds of boulders, and the name was engraved on the city gate. Build arrows on the gates.