816 Gong Cheng 816工程

About 816 Gong Cheng

The central authorities approved the base in 1966 and it took the code number 816, at the time a top state secret; the district government records the construction as authorised by the Central Military Commission and Premier Zhou Enlai. The hills at Baitao were chosen because they sit close to the Wujiang river, which could supply the cooling water a reactor needed, and because a ring of mountains made the works easy to hide. To outsiders the site traded under a cover name, the state-run Jianxin Chemical Machinery Plant, and the sixty thousand engineer-corps troops who worked there could reach the outside world only through a secret code-number mailbox. For the sake of secrecy, Baitao itself was taken off the map.

Excavation ran for eighteen years and hollowed out Jinzi Mountain; Fuling District's own account describes the result as the largest known man-made cavern. When work stopped in 1984 the civil engineering stood at 85 per cent complete and the installation work at 60 per cent, after 740 million yuan of investment, and the design and construction had already taken a collective award at the 1978 National Science Conference. The workings total 25 kilometres of axial length across 104,000 square metres of excavation, with eighteen large chambers and more than 130 roads, guide tunnels, branch tunnels and vertical shafts. The Commission of Science, Technology and Industry for National Defence issued a declassification order in 2002 and the site was opened to the public in stages; it was rated a national 4A tourist attraction in 2019, and in 2024 it was named in the eighth batch of Chongqing patriotic education bases, having earlier been named a municipal national-defence education base.

What to look for

• The central control room, one of more than ten interpretation points set out along the underground route.
• The main cavern, which rises through twelve storeys to a height of 79.6 metres.
• No. 5 guide tunnel and the chemical-process air-intake centre, two of the named stops inside the mountain.
• Two exhibition halls, one on the 816 Project itself and one titled 'The Engineer Corps Forever', whose display boards cover the period background, the strategic decision, the search for a site, the construction and the order to stop.

Location & getting there

Getting to 816 Gong Cheng

Confirm the venue or campus, reservation channel and exhibition calendar. A museum name may cover more than one building.

• Search for 816工程 with 重庆市 and 涪陵区.