816 Underground Nuclear Project


816 Underground Nuclear Project, located in Baitao Town, Fuling District, Chongqing, is one of China's most fascinating historical and engineering marvels. Once a top-secret nuclear facility during the Cold War, this massive underground complex is now open to the public as a 4A-rated national tourist attraction, offering visitors a rare glimpse into China's military-industrial past and its remarkable engineering achievements.


Highlights of the 816 Underground Nuclear Project

  1. Historical Significance

  • Constructed in 1966 as part of China's "Third Front" strategic defense initiative, the 816 Project was designed to be a nuclear fuel production facility hidden deep within Jinzi Mountain to protect it from potential attacks.

  • The project involved 60,000+ workers and took 17 years to build, with an estimated cost of 7.4 billion yuan (equivalent to billions in today's currency).

  • It was declassified in 2002 and opened to tourists in 2010, becoming the world’s largest declassified underground nuclear facility.

  • Engineering Marvels

    • The complex spans 20+ kilometers of tunnels, with 18 large caverns and 130+ passageways, including reactor halls, control rooms, and cooling systems.

    • The main reactor hall is 79.6 meters tall, large enough to hold a 20-story building, and was designed to withstand hydrogen bomb explosions and 8.0-magnitude earthquakes.

    • The 9th Water Diversion Tunnel, stretching 3 km, supplied cooling water from the Wujiang River to the reactors.

  • Key Areas to Explore

    • Reactor Hall (104 Plant): The heart of the facility, where nuclear fuel would have been processed. The sheer scale of this cavern is awe-inspiring.

    • Central Control Room: Preserved with 1,034 original instruments, showcasing the advanced (for its time) automation technology.

    • Exhibition Halls: Displaying historical artifacts, including Cold War-era equipment, worker diaries, and propaganda posters.

  • Atmosphere & Experience

    • The site retains a clandestine, almost cinematic Cold War vibe, with dim lighting, echoing tunnels, and preserved machinery.

    • Guided tours (available in Mandarin, with some English materials) provide deep insights into the workers' lives, technological challenges, and political context of the era.



    Best Time to Visit

    • Spring (March–May) & Autumn (September–November): Mild temperatures (15–25°C) make exploring the underground tunnels comfortable.

    • Avoid Summer (June–August): The tunnels stay cool (~16°C), but surface areas can be hot and humid.

    • Weekdays: Less crowded than weekends, allowing for a more immersive experience.



    Travel Tips

    1. Getting There

    • From Chongqing: Take a 2-hour bus from Chongqing North Bus Station to Fuling, then a taxi (30 min, ~¥50) to the site.

    • By Car: Drive via G50 Shanghai-Chongqing Expressway (2.5 hours from downtown Chongqing).

  • Ticketing & Hours

    • Entrance Fee: ¥60 (adults), with discounts for students/seniors. Guided tours cost extra.

    • Opening Hours9:00 AM–4:30 PM (last entry at 3:30 PM).

  • What to Bring

    • Jacket: The tunnels are cool year-round (~16°C).

    • Comfortable Shoes: The site involves walking on uneven surfaces.

    • Camera: Photography is allowed (no flash in sensitive areas).

  • Nearby Attractions

    • Wuling Mountain Grand Canyon: A stunning natural gorge with hiking trails (30 min drive).

    • Two Rivers Night Cruise: A scenic boat tour on the Wujiang and Yangtze Rivers.

  • Cultural Etiquette

    • Respect the site’s historical gravitas—avoid loud noises or inappropriate behavior.

    • Follow safety signs; some areas may be restricted.


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