816 Underground Nuclear Project
Why visit here?
Located in Fuling, Chongqing, 816 Underground Nuclear Project is the world’s largest artificial cave complex and China’s only declassified & open nuclear military site. Approved by Premier Zhou Enlai in 1966, construction spanned 18 years (8 years digging, 9 years installing equipment) with 60,000 soldiers & workers involved, costing CNY 746 million. Covering 104,000 ㎡ with a total length of 20+ km, the 9-story cave features 18 large chambers, 130+ tunnels & a main hall 79.6 m high (21 stories). Designed to withstand a 1-million-ton hydrogen bomb blast & magnitude-8 earthquake, it was 85% complete when halted in 1984 due to national strategy shifts; declassified in 2002. A masterpiece of national defense & industrial heritage, it’s a key site for patriotism & national defense education.
Pros & Cons
- The biggest man-made cave complex globally, with 20km tunnels & a 79.6m main hall—an unparalleled underground engineering marvel.
- China’s only open nuclear military relic, offering unfiltered access to Cold War secrets & top-tier national defense history.
- Built by 60,000 anonymous heroes over 18 years, it embodies selflessness, patriotism & China’s 1960s–80s national defense resolve.
- Engineered to survive 1Mt nuclear blasts & magnitude-8 quakes—an outstanding example of 20th-century military engineering.
- Year-round coolness (18°C) makes it a perfect summer escape, with dry corridors & dramatic industrial photo ops.
- 9:00–17:00 (last entry 16:30); closed Mondays except holidays. Book tickets 1–3 days in advance online.
- The cave stays 18°C year-round; bring a light jacket even in summer to avoid coldness.
- Wet, steep slopes & dim lighting in some areas; wear sturdy, non-slip footwear for safety.
- The maze-like complex has 130+ tunnels; always follow guides or signs—getting lost is easy.
- Flash damages relics; drones & tripods are banned in most areas. Respect “No Photography” signs.
Recommended Tours incl.
816 Underground Nuclear Project
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