This is one of the open air gun emplacements of Zhenyaun Fort, on Nanshang Mountain. It is part of the collective forts that go to make up the Weiyuan Fort on Weiyuan Island at the east of Humen port. Humen, a town within the city of Dongguan, Guangdong, China. The fort is part of the second tier defence of Humen Fort and was built in 1815. It was lost in the great naval battle of Humen (1841) and damaged by the British forces. By 1843 it was repaired but was again damaged by British forces in 1856. The main Zhenyaun Fort gun emplacements run down the backbone of the ridge of Nanshang Mountain, this one appears to be the lower and still undergoing some ground stabilisation work. Back up the ridge line and behind the emplacements are the refurbished buildings of the Qing Army, strategically placed on the back side of the hill to protect them from attack and from enemy artillery. From this point, the huge sweep of the Humen Bridge can be viewed. The bridge, completed in 1997, was the first large suspension bridge designed and constructed by China independently. It is 4.58 kilometers (2.8 miles) long with the deck of the bridge carrying six, two-way traffic lanes. The main span stretches 888 meters (2913 feet). Incidently, on the island in the middle of the river you can see the remains of one of the other forts, part of the same grouping for defence of the Pearl River. The First Opium Wars (1839 to 1842) which were started as a result of Lin Zexu siezing and destroying many tons of Opium on the nearby beach at Humen.The Second Opium War was 1856 to 1860.