Hidden deep in the mountains of Fuling district, Chongqing, the 816 Project was once one of China's most secret industrial sites. Built during the Third Front Movement (1964-80) when important military and industrial facilities were built in or relocated to the inland regions, it was designed as China's second nuclear raw-material production base, producing plutonium-239 for nuclear weapons. The project remained off-limits to the public for decades before being declassified in 2002. Today, this vast underground complex has been transformed into a unique attraction, where visitors can walk through tunnels and cavernous halls and glimpse a remarkable chapter of modern Chinese history.
The complex consists of 18 enormous caverns linked by more than 130 passageways. Its most striking space is the main reactor cavern, which rises 79.6 meters — roughly the height of a 26-story building — beneath a rock cover as thick as 200 meters. Now open to visitors, parts of the reactor complex, including the main section of Unit 101, can be explored via glass walkways, offering a dramatic view down into the reactor's former water-supply system. Towering rock walls illuminated by blue and white lights add to the otherworldly atmosphere, making a visit to the 816 Project unlike almost any other sightseeing experience in China.
Who it’s for
Ideal for: History buffs, architectural enthusiasts, and seekers of the unconventional.
Not for: Those uneasy with enclosed spaces and dim lighting.
Best time to go
April to October is prime, offering better daylight hours (9 am-5 pm) for explorations.
Don’t miss
1. Step inside the massive reactor hall
Enter the heart of the 816 Project and stand beneath its nearly 80-meter-high reactor hall — the largest cavern in the complex. Explore the reactor bottom cavity and other monumental spaces, where towering concrete structures, exposed rock walls and industrial installations create an atmosphere straight out of a science-fiction film.
2. Explore the underground world of the Third Front Movement
Follow the winding tunnels deep into the mountains and discover the remarkable story behind this once-secret project, built by more than 60,000 workers during China’s Third Front Movement.
3. Experience the immersive Cave 816 show
Since 2024, the 60-minute immersive live-action show Cave 816 has brought the site's history to life through dramatic lighting, sound, projections and live performance. Staged within the monumental underground setting, the show offers a more atmospheric way to understand the people, history and stories behind this extraordinary industrial relic.
Before you go
1. Wear sturdy, comfortable shoes as the terrain can be uneven in parts.
2. Foreign language tour options may be limited; brush up on key terms or bring a translation app.
Practical essentials
816 Project
Address: X182, Fuling district, Chongqing
Opening hours:
April 1-Oct 31: 9 am to 5 pm
Nov 1-March 31: 9 am to 4:30 pm
Admission: 65 yuan ($9.65)/person
Getting there:
By car (recommended): From downtown Chongqing, take the G50 Shanghai-Chongqing Expressway/Yangtze River Expressway, then switch to the Yinchuan-Baise Expressway and continue via the Zili-Baitao Expressway to Baitao subdistrict. Follow your navigation to the “816 Project Scenic Area Parking Lot B/C” (816 工程景区 B 区/C 区停车场). The journey takes approximately 2 hours.