816 Nuclear Military Plant (simplified Chinese:816地下核工厂;traditional Chinese:816地下核工廠) is an unfinishedChinese underground nuclear weapons production facility and the largest man-made tunnel structure in the world.[1] Amilitarymegaproject, the nuclear base is located near what is nowsuburbanFuling, amunicipality inChongqing,China. In 2010, it was opened to Chinese tourists. It is a distinct network of nuclear-weapons manufacturing tunnels to the likewise defunctUnderground Project 131 and the still operational "Underground Great Wall of China."
The project was started in 1966 whenSino-Soviet relations dramatically declined (see also theSino-Soviet split). To enhance China'snational defence and prevent possible Soviet invasion and nuclear attack, the project was approved (directly by then-PremierZhou Enlai) and undertaken in secret. More than 60,000engineering soldiers of thePeople's Liberation Army participated in the construction of the base.[1] The underground base was designed to be able to tolerate thousands of tons ofTNT explosives and 8-magnitudeearthquakes.[1]
The project was under construction for 17 years, and the construction was nearly completed in 1984. In 1964 China made itsfirst public nuclear test. Largely due to change in theCold War international situation, the project was cancelled in February 1984.[2] It was further declassified in April 2002.[2] In April 2010, after being closed for over 25 years, the base was opened to tourists.[1][2]
The surface area of the cave is more than 104,000 m2, and the total length of thetunnels is more than 20 kilometers.[3] The whole complex consists of 13 levels, 18 artificial caves linked to each other, and has more than 80roads and 130 tunnels.[3]Automobiles are able to pass the roads and tunnels inside.[3] The base has the “World's Largest ArtificialCave”,[1] which has a height of 79.6 meters, roughly equal to that of a 20-floor building.[3]